Marking control device, laser application device, marking control method, and computer-readable recording medium having marking control program

ABSTRACT

A disclosed marking control device controls a marking device to mark a target image on a thermoreversible recording medium by applying a laser beam includes a marking position determination unit dividing the image into plural marking lines, and determining their marking positions; a marking order determination unit determining a marking order to mark the marking lines in mutually opposite directions; an adjusting unit adjusting a distance between a first ending point and a second starting point to be longer than a distance between a first starting point and a second ending point, or adjusting laser power applied to a second starting point side of the second marking line to be lower than the laser power applied to a second ending point side of the second marking line; and a marking instruction generator unit generating marking instructions including the marking positions of the marking lines and the marking order thereof.

TECHNICAL FIELD

A certain aspect of the present invention relates to a marking controldevice, a laser application device, a marking control method, and acomputer-readable recording medium embodying a marking control program.

BACKGROUND ART

Commercially available laser application devices (also called “lasermarkers” or “laser marking devices”) are developed based on a technologywhere characters, numbers, and symbols are thermally recorded on amedium such as a thermosensitive paper by the application of laserbeams.

A laser beam emitted from a laser light source of the laser applicationdevice is applied to media such as plastic or thermosensitive paper,such that characters, symbols, etc., are recorded on such media.Examples of the laser light source include a gas laser, a solid-statelaser, a liquid laser, and a semiconductor laser (i.e., a laser diode,LD).

With metallic or plastic media, heat generated upon the application of alaser beam engraves or singes surfaces of the media, so that charactersand symbols are recorded on the metallic or plastic media. On the otherhand, the thermosensitive paper has a characteristic of changing itscolors with heat, and the heat generated upon the application of a laserbeam causes recording layers of the thermosensitive paper to generatecolors. Accordingly, characters and symbols are recorded on thethermosensitive paper.

Compared to the metallic or plastic media, the thermosensitive paper isrelatively easy to handle and hence is widely used as labeling media.For example, distribution destinations of articles or article names arerecorded on the thermosensitive paper used as labeling media in thephysical distribution field.

Recently, rewritable thermosensitive paper (hereinafter called “thermalrewritable media” or “thermoreversible recording media”) have been madeavailable, on which information can be repeatedly recorded or erased.

At present, with the thermoreversible recording media, images arerecorded on or erased from the reversible recording medium by directcontact with a heat source (i.e., a contact recording/erasing process).In this case, a thermal head is generally used as the heat source inimage recording, and a thermal roller, ceramic heater, and the like maybe used as the heat source in image erasing.

Such a contact recording/erasing process has the following advantages.That is, when the thermoreversible recording medium is a flexible mediumsuch as a film or paper, the flexible recording medium may be uniformlypressed against the heat source with a platen to uniformly record imageson or erase the images from the flexible recording medium. In addition,since components of a conventional printer specifically used forthermosensitive paper may be diverted to become components of a newimage recording apparatus or those of a new image erasing apparatus,manufacturing costs of the new image recording or image erasingapparatus may be reduced.

FIG. 1 is a diagram illustrating a coloring/decoloring principle in athermal rewritable medium.

The thermal rewritable medium includes a recording layer that reversiblychanges its color tone into a transparent status or a colored statuswith heat. The recording layer includes leuco dyes of organiclow-molecular substances and reversible developers (hereinafter simplycalled “developers”).

As illustrated in FIG. 1, when the recording layer in a decolored stateA is heated to a melting temperature T2, the leuco dyes and thedevelopers in the recording layer are melted and mixed so that therecording layer is colored in a melted colored state B. When therecording layer in the melted colored state B is rapidly cooled, atemperature of the recording layer is decreased to room temperaturewhile the recording layer maintains its colored state, therebystabilizing the colored state of the recording layer.

Accordingly, the recording layer is in a solid colored state C. Whetherthe recording layer is capable of obtaining such a solid colored state Cdepends on a speed of heating or cooling the recording layer in themelted colored state B. If the recording layer is slowly cooled, therecording layer is decolored to be in the initial decolored state A. If,on the other hand, the recording layer is rapidly cooled, the recordinglayer acquires a relatively dense color compared to that in the solidcolored state A.

Meanwhile, when the recording layer in the solid colored state C isheated again, the recording layer is decolored at a temperature T1 lowerthan a coloring temperature (from D to E), and if the recording layer inthe solid colored state C is then cooled, the recording layer returns tothe initial decolored state A.

In the recording layer in the solid colored state C changed from themelted state by rapid cooling, colored leuco dye molecules and developermolecules are mixed while they remain in contact reactive states, andthe molecules in the contact reactive states often form solids. In thisstate, the melted mixture (colored mixture) of the leuco dyes anddevelopers is crystallized while retaining its colored state, and hence,the color of the mixture may be stabilized due to this crystallizedstructure. In the decolored state, phases of the leuco dyes and thedevelopers are separated from one another. In the phase-separationstate, the molecules of one of the leuco dye compound and the developercompound are cohered or crystallized. Accordingly, the leuco dyes andthe developers are separately stabilized due to their cohesion orcrystallization. In many cases, more complete decoloration (colorerasure) of the recording layer may be obtained due to the phaseseparation of the leuco dyes and the developers, and crystallization ofthe developer.

Note that erasing failure, where the recording layer repeatedly heatedat an erasing temperature is unable to decolor, may occur if therecording layer is repeatedly heated to a temperature T3 that is equalto or higher than the melting temperature T2. The erasing failure mayresult from thermal decomposition of the developer, because thethermally decomposed developer is resistant to cohesion orcrystallization and thus the thermally decomposed developer may not beeasily separated from the leuco dye. Deterioration of thethermoreversible recording medium due to repeated heating and coolingmay be controlled by decreasing the difference between the meltingtemperature T2 and the temperature T3 while heating the thermoreversiblerecording medium.

Such thermoreversible recording media are widely used in the physicaldistribution field, and various improvements have been made to arecording (marking) method in the recording of the thermoreversiblerecording media.

For example, when adjacent first and second lines are marked, theresidual heat of the first line initially marked may interfere with theheating of the second line while the second line is being marked. Thisinterference may result in decoloration of the recording in thethermoreversible recording media. Japanese Patent ApplicationPublication No. 2008-62506 (hereinafter referred to as “Patent Document1”), for example, discloses a technology in which such decoloration iscontrolled by adjusting a time or an overlapping width between a markingstart point of the first line and a marking end point of the secondline.

However, if the thermoreversible recording medium contains an RF-ID tag,the thermoreversible recording medium has an increased thickness andthus is less flexible. Accordingly, higher pressure may be required whenthe heat source is uniformly pressed against the thermoreversiblerecording medium (see Japanese Patent Application Publication No.2004-265247 (hereinafter referred to as “Patent Document 2”) andJapanese Patent No. 3998193 (hereinafter referred to as “Patent Document3”)).

Further, if printing and erasure are repeated in such a contactrecording/erasing process, the recording medium obtains an unevensurface due to ablation. Accordingly, erasing failure or densitydecrease may occur due to non-uniform application of heat resulting fromportions of the recording medium not contacting the heat source such asa thermal head or hot stamp (see Japanese Patent No. 3161199(hereinafter referred to as “Patent Document 4”) and Japanese PatentApplication Publication No. 9-30118 (hereinafter referred to as “PatentDocument 5”)).

Japanese Patent Application Publication No. 2000-136022 (hereinafterreferred to as “Patent Document 6”) discloses a technology in which animage is uniformly recorded on and erased from an uneven surface of thethermoreversible recording medium using a laser, or an image isuniformly recorded on the thermoreversible recording medium from adistance using a laser. This technology is used for transportationcontainers. With this technology, contactless recording is performed onthermoreversible recording media that are attached to the transportationcontainers, where recording is carried out by laser beams but erasure iscarried out by hot air, hot water, or an infrared heater.

Inspired by contactless reading or contactless rewriting of recordinginformation performed on RF-ID tags from a distance, there is a desirethat images also be rewritten on the thermoreversible recording mediafrom a distance.

In such a laser recording technology, a laser recording device(generally called a “laser marker”) is used. The laser marker isconfigured to control a laser beam such that the laser beam is appliedto an appropriate position of the thermoreversible recording medium whenthe laser marker applies a high-power laser beam to the thermoreversiblerecording medium. In this laser marker, the thermoreversible recordingmedium absorbs a laser beam and converts the absorbed laser beam intoheat, so that information is recorded or erased by the converted heat.Japanese Patent Application Publication No. 11-151856 (hereinafterreferred to as “Patent Document 7”) discloses a laser recording-erasingtechnology in which images are recorded on or erased from thethermoreversible recording media, and formed based on a combination of aleuco dye, a reversible developer, and various photothermal conversionmaterials by the application of infrared laser beams.

Further, Japanese Patent Application Publication No. 2008-213439(hereinafter referred to as “Patent Document 8”) discloses an imageprocessing method (image marking control method) in which when laserbeams aligned at predetermined intervals are applied in parallel to scanin the same directions, discontinuous application of the laser beams maybe partially included. For example, when the laser beam scans from afirst starting point to a first ending point, the laser beam is causedto scan a second starting point by jumping from the first ending pointto the second starting point where the first ending point and the secondstarting point are separated by a predetermined interval (gap).

With above related art technologies, the thermoreversible medium may beuniformly heated so that image quality and repeated durability of imageformation on the medium are improved; however, image recording orerasing time may be increased due to time required for jumping acrossdrawing line intervals and waiting time during jumping.

Moreover, Japanese Patent No. 3557512 (hereinafter referred to as“Patent Document 9”) discloses a technology in which a laser beam scansin a looped or a convoluted fashion so as to apply the laser beam to anentire cell region. In this case; however, excessive heat is applied tocurved portions of the loop or convolution so that the repeateddurability of image formation in the thermoreversible recording mediumis lowered.

Thus, in the related art technologies, there may be few image recordingtechnologies capable of printing with high printing quality and highrepeated durability of image formation, and recording an image on amedium in a short time; or there may be few image erasing technologiescapable of uniformly applying heat to the recording medium, acquiring awide erasing width of the medium, and erasing the recorded image in ashort time.

The above related art technologies may include the following drawbacks.

The laser marker generally scans plural lines in parallel to fill anarea with a solid color. However, with a thermal rewritable medium,simply scanning plural lines in parallel may not achieve the solidlyfilled color.

As illustrated in FIG. 1, the thermal rewritable medium has thedecoloring temperature between the room temperature and the coloringtemperature. Thus, when the thermal rewritable medium is heated with alaser beam, peripheries of the marked lines become decoloringtemperature regions of the rewritable medium due to output intensitydistribution of the laser spot or thermal diffusion on the rewritablemedium. Further, if a coloring property of the rewritable medium isbroad with a temperature, the densities of the scanned lines may not beuniform in width directions of the scanned lines. In order to fill anarea with the uniform density, a line is marked by slightly overlappinga previously marked line such that a residual heat region in theperiphery of the previously marked line is cancelled (see PatentDocument 1).

Note that since the residual heat of the scanned line decreases withtime, it is important to control time intervals in marking lines usingthe residual heat. In view of discoloring due to accumulated heat, if amarking speed is high or a marked line is short, it is preferable that atime interval in marking lines be long, whereas if the marking speed islow or the marked line is long, it is preferable that a time interval inmarking lines be short.

FIGS. 2A, 2B, and 2C are diagrams illustrating a marking method in whicha subsequent line is marked (scanned) by partially overlapping aprevious line. FIGS. 3A and 3B are diagrams illustrating a markingmethod in which lines are marked by reciprocating scanning.

In FIG. 2A, flat ovals indicate a profile of coloring line, solid linearrows indicate operations of marking (marking operations), and brokenarrows indicate jumping operations (non-emitting operations) betweenmarking points, so that an area is filled with a solid color byrepeating the following steps 1 to 3.

Step 1. A laser marker is illuminated to scan a line from a firststarting point in a plus direction of an X-axis with a predeterminedlaser power at a predetermined speed.

Step 2. The laser marker is turned off and moved to a second startingpoint (in a minus direction of a Y-axis direction).

Step 3. The laser marker waits for a predetermined waiting time.

Accordingly, the area is filled in solid as illustrated in FIG. 2B. Inthe marking method illustrated in FIG. 2A, since the laser markercarries out jumping operations (non-emitting operation) and waitingwhile repeating to mark marking lines in the plus directions of X-axisas illustrated in FIG. 2C, solidly filling an area with the markinglines may require a long time. However, if thick lines such as a barcodeare marked, the above method may be necessary for solidly filling thearea with the marking lines. Thus, a higher marking speed may berequired for shortening the marking time.

In the example of solidly filling the area illustrated in FIGS. 2A, 2B,and 2C, the lines are repeatedly marked in the same directions tosolidly fill the area, so that the laser marker (or beam) needs to jump(carry out a non-emitting operation) a distance corresponding to alength of the marked line or longer. Thus, this method is not suitablefor high speed marking.

However, in ink-jet printers, it is commonly known in the art that linesare marked in two opposite directions while reciprocating a printer headin the two directions. Accordingly, the lines may be marked by a lasermarker at higher scanning speeds with a reciprocating scanning methodillustrated in FIG. 3A.

However, when the marking direction is reversed (i.e., oppositedirection), marking is started with a side where marking of the previousline is finished. Thus, the laser marker needs to have a longer waitingtime for allowing the residual heat to dissipate, which may notcontribute to a reduction in an overall marking time as illustrated inPatent Document 1.

Further, an effect of the residual heat of the previously marked line isgreater in the next starting point of a subsequent marking line andsmaller in the next ending point of the subsequently marked line.Accordingly, color variability may be obtained when the lines are markedwith a weak (low) laser power as illustrated in FIG. 3B. On the otherhand, if the lines are marked with a high (strong) laser power, the areamay be uniformed filled with solid lines without color variability.However, if marking and erasing are repeated, the starting pointportions with high densities illustrated in FIG. 3B may be some quicklydeteriorated and thus these portions of lines may no longer be erasable.

The inventors of the present invention have found the following based onvarious examinations.

A related art method illustrated in FIGS. 4A, 4B, and 4C is used as alaser beam scanning method for solidly filled image printing and solidlyfilled image erasure using a round laser beam. In FIGS. 4A to 4C, alaser marker scans thick solid lines with laser beams at uniform speeds,whereas the laser marker carries out non-emitting operations indicatedby broken lines without emitting a laser beam.

A laser scanning method illustrated in FIG. 4A is capable of scanning alaser beam in a short time so that a solidly filled image printing orsolidly filled image erasure may be carried out in a short time.However, excessive energy may be applied to the medium due to effects ofa (low) scanning speed of a laser beam in turning portions of the linesand heat accumulated in the turning portions of the lines. These effectsare obtained by marking a starting point of a second laser beam markingline 412 immediately after marking an ending point of a first laser beammarking line 411. Accordingly, density (color) variability (densitylowered in the image portion and color appearing in the image erasedportion) may be obtained in the solidly filled image portion or in theimage erased portion on the medium.

A laser scanning method illustrated in FIG. 4B is capable of scanning asolidly filled image printing in a short time with little effect oflowering a scanning speed at turning portions of the lines. However,there is still the effect of heat accumulated in the turning portions ofthe lines obtained by marking the starting point of the second laserbeam marking line 421 immediately after marking the ending point of thefirst laser beam marking line 422, such that excessive energy may beapplied to the medium. Accordingly, density (color) variability (densitylowered in the image portion and color appearing in the image erasedportion) may be obtained in the solidly filled image portion or in theimage erased portion of the medium. Further, the repeated durability ofthe solidly filled image may be lowered.

Moreover, laser scanning method illustrated in FIG. 4C eliminatesadverse effects of the scanning speed and the heat accumulation in theturning portions of the lines, such that excessive energy may not beapplied to the medium. Accordingly, the density (color) variability maynot be obtained in the solidly filled image portion or in the imageerased portion of the medium. Further, the repeated durability of thesolidly filled image may be improved. However, with this method, timefor non-emitting portions (no laser application) may be longer, therebyincreasing the image printing time and image erasure time. In addition,with this method, since the effect of heat accumulation in the turningportions of the lines is lowered, the second laser beam marking line 432is marked or erased in a cooled state after the scanning of the firstlaser beam marking line 431. Accordingly, the accumulated heat is notutilizable for marking or erasing of the second laser beam marking line432. As a result, high energy is required for the marking or erasing ofthe subsequent laser beam marking lines. Thus, the solidly filled imageprinting time or image erasure time may not be reduced due to inabilityto increase the scanning speed.

However, as illustrated in FIG. 5B, if the laser beam marking line 451is marked and scanned from the first starting point to the first endingpoint, and the second laser beam marking line 452 is subsequently markedadjacent to the first laser beam marking line 451 from the secondstarting point to the second ending point such that the second endingpoint of the second laser beam marking line 452 is located in a lineslanted toward the first starting point of the first laser beam markingline 451 based on a line in parallel with the first laser beammarkingline 451, density variability in the solidly filled image area (portion)or the image erased area (portion) may be suppressed. Accordingly, therepeated durability of the solidly filled image may be improved and thesolidly filled image printing time or image erasure time may be lowered.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a marking control device, alaser application device, a marking control method, a marking controlprogram, and a recording medium embodying such a marking control programthat solve or reduce one or more problems caused by the limitations anddisadvantages of the related art. Specifically, a marking controldevice, a laser application device, a marking control method, a markingcontrol program, and a recording medium embodying such a marking controlprogram that enable laser scanning image formation with high quality andhigh repeated durability, obtaining a wide image erasable energy widthwhen erasing an image, and image recording or erasing processing in ashort time.

The embodiments have attempted to provide a marking control device, alaser application device, a marking control method, a marking controlprogram, and a recording medium embodying such a marking control programcapable of reducing a marking time in marking an image while maintaininghigh quality of the marked image.

According to an embodiment of the present invention, there is provided amarking control device for controlling a marking device that marks atarget image on a thermoreversible recording medium by applying a laserbeam to the thermoreversible recording medium. The marking controldevice includes a marking position determination unit configured todivide the target image into a first marking line and a second markingline that are adjacent to each other, and determine a marking positionof each of the adjacent first and second marking lines; a marking orderdetermination unit configured to determine a marking order of theadjacent first and second marking lines for marking the target imagesuch that the second marking line is marked in a direction opposite to adirection in which the first marking line is marked; an adjusting unitconfigured to adjust, when the first marking line is initially scannedand the second marking line is reciprocally scanned subsequent to thefirst marking line, a first distance between a first ending point of thefirst marking line and a second starting point of the second markingline to be longer than a second distance between a first starting pointof the first marking line and a second ending point of the secondmarking line, or a laser output power of the laser beam applied to asecond starting point side of the second marking line to be lower than alaser output power of the laser beam applied to a second ending pointside of the second marking line; and a marking instruction generatorunit configured to generate a set of marking instructions including therespective marking positions of the first and second marking lines andthe marking order of the first and second marking lines.

According to another embodiment, there is provided a laser applicationdevice that includes a laser oscillator configured to generate a laserbeam; a direction control mirror configured to control a direction ofthe generated laser beam; a direction control motor configured to drivethe direction control mirror; and a marking control device configured tocontrol an output power of the laser oscillator, and the driving of thedirection control motor based on the set of the marking instructions.

According to another embodiment, there is provided a marking controlmethod for controlling a marking device that marks a target image on athermoreversible recording medium by applying a laser beam to thethermoreversible recording medium. The marking control method includesdividing the target image into a first marking line and a second markingline that are adjacent to each other, and determining a marking positionof each of the adjacent first and second marking lines; determining amarking order of the adjacent first and second marking lines for markingthe target image such that the second marking line is marked in adirection opposite to a direction in which the first marking line ismarked; adjusting, when the first marking line is initially scanned andthe second marking line is reciprocally scanned subsequent to the firstmarking line, a first distance between a first ending point of the firstmarking line and a second starting point of the second marking line tobe longer than a second distance between a first starting point of thefirst marking line and a second ending point of the second marking line,or a laser output power of the laser beam applied to a second startingpoint side of the second marking line to be lower than a laser outputpower of the laser beam applied to a second ending point side of thesecond marking line; and generating a set of marking instructionsincluding the respective marking positions of the first and secondmarking lines and the marking order of the first and second markinglines.

According to another embodiment, there is provided a computer-readablerecording medium having a marking control program embodied thereinincluding a set of instructions for controlling a marking device to marka target image on a thermoreversible recording medium by applying alaser beam to the thermoreversible recording medium, which, whenexecuted by a processor, causes a computer to function as a markingposition determination unit configured to divide the target image into afirst marking line and a second marking line that are adjacent to eachother, and determine a marking position of each of the adjacent firstand second marking lines; a marking order determination unit configuredto determine a marking order of the adjacent first and second markinglines for drawing the target image such that the second marking line ismarked in a direction opposite to a direction in which the first markingline is marked; an adjusting unit configured to adjust, when the firstmarking line is initially scanned and the second marking line isreciprocally scanned subsequent to the first marking line, a firstdistance between a first ending point of the first marking line and asecond starting point of the second marking line to be longer than asecond distance between a first starting point of the first marking lineand a second ending point of the second marking line, or a laser outputpower of the laser beam applied to a second starting point side of thesecond marking line to be lower than a laser output power of the laserbeam applied to a second ending point side of the second marking line;and a marking instruction generator unit configured to generate a set ofmarking instructions including the respective marking positions of thefirst and second marking lines and the marking order of the first andsecond marking lines.

BRIEF DESCRIPTION OF DRAWINGS

Other objects and further features of embodiments will be apparent fromthe following detailed description when read in conjunction with theaccompanying drawings, in which:

FIG. 1 is a diagram illustrating a coloring/decoloring principle in athermal rewritable medium;

FIGS. 2A, 2B, and 2C are diagrams illustrating a marking method in whicha line is subsequently marked by partially overlapping a previous line;

FIGS. 3A and 3B are diagrams illustrating a marking method in whichlines are marked by reciprocating scanning;

FIG. 4A is a diagram illustrating an example of a related art laser beamscanning method for recording or erasing an image;

FIG. 4B is a diagram illustrating another example of the related artlaser beam scanning method for recording or erasing an image;

FIG. 4C is a diagram illustrating still another example of the relatedart laser beam scanning method for recording or erasing an image;

FIG. 5A is a diagram illustrating a laser beam scanning method forrecording or erasing an image according to a third embodiment;

FIG. 5B is a diagram illustrating a laser beam scanning method forrecording or erasing an image according to a fourth embodiment;

FIG. 6 is a configuration diagram illustrating a laser applicationdevice 1 according to a first embodiment;

FIG. 7 is a configuration block diagram illustrating a marking controldevice 4 according to the first embodiment;

FIG. 8 is a diagram illustrating an example of a marking data structurefor use in the marking control device according to the first embodiment;

FIG. 9 is a diagram illustrating an example of a control data structurefor use in the marking control device according to the first embodiment;

FIG. 10 is a flowchart illustrating a marking data generation processcarried out by the marking control device according to the firstembodiment;

FIG. 11 is a diagram illustrating an example of data associating a unitline-identifier with a laser power for use in the marking control deviceaccording to the first embodiment;

FIGS. 12A, 12B, and 12C are diagrams each illustrating a marking methodbased on the marking data generated by the marking control deviceaccording to the first embodiment;

FIG. 13 is a diagram illustrating a marking method based on marking datagenerated by a modification of the marking control device according tothe first embodiment;

FIG. 14 is a configuration block diagram illustrating a marking controldevice according to a second embodiment;

FIGS. 15A, 15B, and 15C are diagrams each illustrating a marking methodbased on marking data generated by the marking control device accordingto the second embodiment;

FIG. 16 is a flowchart illustrating a marking data generation processcarried out by the marking control device according to the secondembodiment;

FIG. 17A is a schematic sectional diagram illustrating an example of alayer structure of a thermoreversible recording medium according to anembodiment;

FIG. 17B is a schematic sectional diagram illustrating another exampleof the layer structure of a thermoreversible recording medium accordingto the embodiment;

FIG. 17C is a schematic sectional diagram illustrating still anotherexample of the laminate configuration of a thermoreversible recordingmedium according to the embodiment;

FIG. 18 is a schematic diagram illustrating an example of an RF-ID tag;

FIG. 19A is a graph illustrating coloring/decoloring properties of thethermoreversible recording medium;

FIG. 19B is a schematic diagram illustrating a coloring/decoloringmechanism of the thermoreversible recording medium;

FIG. 20 is a schematic diagram illustrating an image processingapparatus according to an embodiment;

FIG. 21A is a diagram illustrating an example of a laser beam scanningmethod for recording or erasing an image in Examples;

FIG. 21B is a diagram illustrating another example of the laser beamscanning method for recording or erasing an image in Examples;

FIG. 22A is a diagram illustrating an example of a laser beam scanningmethod for recording or erasing an image carried out in a ComparativeExample;

FIG. 22B is a diagram illustrating another example of the laser beamscanning method for recording or erasing an image carried out in theComparative Example; and

FIG. 22C is a diagram illustrating still another example of the laserbeam scanning method for recording or erasing an image carried out inthe Comparative Example.

DESCRIPTION OF EMBODIMENTS

Preferred embodiments of the present invention are described below withreference to the accompanying drawings.

Preferred embodiments of the marking control device, the laserapplication device, the marking control method, and the recording mediumembodying the marking control program are described below with referenceto the accompanying drawings.

Hereinafter, the term a “target image” refers to any marks includingcharacters, numbers, symbols, and graphics that are intended to berecorded or marked on the recording medium.

The term a “line component” refers to a portion formed between twopredetermined points each having predetermined coordinates. The portionforms part of the target image such as a character. The line componentnot only represents a portion of a linear line but also represents aportion of a curved line, and the line component has a certainthickness.

In the mark control device according to the embodiment, the target imageis divided into plural lines so that the target image is completed bymarking (drawing) each line. The “line” indicates one stroke of thecharacter or graphic, which is recorded by applying a laser beam from astarting point to an ending point. The “line” may constitute a series ofstrokes recorded between the starting point and the ending point. Thestroke may be the same as or different from “one stroke” defined bypublic organizations such as JIS or ISO.

The term “marking order” includes two meanings: one is the order oflines to be drawn, including which side of the line is to be drawnfirst; and the other is the order of plural target images to be drawn.

First Embodiment

FIG. 6 is a configuration diagram illustrating a laser applicationdevice 1 according to a first embodiment. The laser application device 1according to the first embodiment includes a laser device 2 configuredto emit a laser beam, a scanner device 3 configured to scan the laserbeam emitted from the laser device 2 onto the thermoreversiblerewritable medium 100, and a marking control device 4 configured todrive control components of the laser application device 1.

The laser application device 1 scans the laser beam on the rewritablemedium 100 based on marking instructions received from an external hostcomputer 200 to mark a target image on the rewritable medium 100. Thelaser device 2 is configured to emit a laser beam based on aninstruction received from the marking control device 4. The laser device2 may be a semiconductor laser (i.e., a laser diode, LD) device, a YAGlaser device, or a carbon dioxide gas laser device; however, thesemiconductor laser (i.e., a laser diode, LD) device is preferable amongthese, due to its relative easiness of laser power control.

The scanner device 3 includes an X-axis galvanometer mirror 11 and aY-axis galvanometer mirror 12 each composed of a movable mirror fordeflecting the laser beam, and an fθ lens 13.

The X-axis galvanometer mirror 11 is driven by a galvanometer 14 to scanthe laser beam in an X-axis direction. The Y-axis galvanometer mirror 12is driven by a galvanometer 15 to scan the laser beam in a Y-axisdirection.

The galvanometer 14 is connected to an X-axis servo driver 16, and thegalvanometer 15 is connected to a Y-axis servo driver 17. The X-axisservo driver 16 and the Y-axis servo driver 17 are respective drivecircuits to control angles of the X-axis galvanometer mirror 11 and theY-axis galvanometer mirror 12 based on respective instruction valuesreceived from the marking control device 4. The X-axis servo driver 16and the Y-axis servo driver 17 compare position signals acquired fromrespective angle sensors (not shown) of the X-axis galvanometer mirror11 and the Y-axis galvanometer mirror 12 with the respective instructionvalues received from the marking control device 4, and the X-axis servodriver 16 and the Y-axis servo driver 17 then transmit respective drivesignals to the galvanometers 14 and 15 so as to minimize the errors ofthe compared results.

The fθ lens 13 corrects displacement angles of the X-axis galvanometermirror 11 and the Y-axis galvanometer mirror 12 such that the respectivedisplacement angles are in proportion to a displacement distance of thelight collecting spot while collecting the laser beams deflected by theX-axis galvanometer mirror 11 and the Y-axis galvanometer mirror 12 onthe rewritable medium 100.

The scanner device 3 having the above configuration deflects the laserbeam emitted from the laser device 2 with the X-axis galvanometer mirror11 and further deflects the laser beam deflected by the X-axisgalvanometer mirror 11 with the Y-axis galvanometer mirror 12, such thatthe laser beam deflected by the Y-axis galvanometer mirror 12 is appliedto the rewritable medium 100 via the fθ lens 13. In this process, thelaser beam may be scanned two-dimensionally by appropriately modifyingthe respective angles of the X-axis galvanometer mirror 11 and theY-axis galvanometer mirror 12.

The marking control device 4 includes a processing device such as anASIC (not shown) or a CPU (not shown), a ROM (not shown) storing apredetermined program for controlling operations of the marking controldevice 4, and a storage device such as a RAM used as a working area ofthe processing device. The processing device and the storage deviceconstitute a computer. The marking control device 4 is electricallyconnected to the host computer 200, the laser device 2, the X-axis servodriver 16, and the Y-axis servo driver 17.

Note that the laser device 2, the X-axis galvanometer mirror 11, theY-axis galvanometer mirror 12, the fθ lens 13, the galvanometer 14, thegalvanometer 15, the X-axis servo driver 16, and the Y-axis servo driver17 constitute a marking device of the laser application device 1.

FIG. 7 is a configuration block diagram illustrating the marking controldevice 4 according to the first embodiment.

As illustrated in FIG. 7, the marking control device 4 implementsrespective functions of a host interface section 20, a marking datagenerator section 30, a control data generator section 40, a controldata output section 50, a galvanometer mirror control signal generatorsection 60, a laser power control signal generator section 70, and alaser emission control signal generator section 80, in cooperation withthe processing device and the program stored in the storage device.

Further, the marking control device 4 implements a laser emittingsection 90 as a function of a marking instruction generator unit thatincludes the control data generator section 40, the control data outputsection 50, the galvanometer mirror control signal generator section 60,the laser power control signal generator section 70, and the laseremission control signal generator section 80, in cooperation with theprocessing device and the program stored in the storage device.

The host interface section 20 is configured to receive a markinginstruction from the host computer 200. When a target image is abarcode, the marking instruction is composed of data including anidentifier for identifying a type of the barcode, marking positions andsizes of line components (coordinates of each end) of the barcode. Thehost interface section 20 transmits, on receiving a code indicating anend of the marking instruction, the marking instruction to the markingdata generator section 30.

The marking data generator section 30 includes a marking positiondetermination section 31, a marking order determination section 32, alaser power adjusting section 33, and a marking speed adjusting section34, and is configured to appropriately encode data representing thebarcode contained in the marking instruction to generate marking data.The marking data include control flags including information onpositions (coordinate data), the plural line components of the barcodeon the rewritable medium 100, a marking order of the line components,laser power, marking speed, and turning on or off the laser.

The marking position determination section 31 is a marking positiondetermination unit configured to determine the positions (coordinatedata) of the plural line components of the barcode on the rewritablemedium 100 based on the marking instruction. The marking orderdetermination section 32 is a marking order determination unitconfigured to determine the marking order of each line component of thebarcode. The laser power adjusting section 33 is a laser power adjustingunit configured to adjust laser power for drawing each line componentand set the laser on/off. The marking speed adjusting section 34 isconfigured to adjust a marking speed (i.e., respective drive speeds ofthe X-axis galvanometer mirror 11 and the Y-axis galvanometer mirror 12)to mark the target image on the rewritable medium 100.

The marking control device 4 receives the marking instruction from thehost computer 200, generates the marking data by defining the targetimage by plural line components, controls respective positions of theX-axis galvanometer mirror 11 and the Y-axis galvanometer mirror 12, andcontrols emission time and emission power of the laser beam emitted fromthe laser device 2 to draw the target image on the rewritable medium100.

FIG. 8 is a diagram illustrating an example of a marking data structurefor use in the marking control device 4 according to the firstembodiment.

The marking data include plural unit marking data portions. Asillustrated in FIG. 8, unit marking data D1 include a coordinate dataportion D1 a specifying coordinates (X-coordinate, Y-coordinate) of alaser beam transfer point, a laser power coefficient portion D1 b forsetting an output power of a laser beam and a laser speed coefficientportion D1 b for setting an output speed of the laser beam, and acontrol flag portion D1 c for setting the laser beam on or off beforethe laser beam reaches the specified coordinates.

The unit marking data D1 are 8-byte data in the first embodiment. TheX-coordinate of the coordinate data portion D1 a includes two-bytesigned binary data and the Y-coordinate of the coordinate data portionD1 a includes two-byte signed binary data. The laser power coefficientportion D1 b is used for setting the output power of the laser beam inpermillage based on a reference output. The control flag portion D1 cincludes a final coordinate flag indicating whether specifiedcoordinates are final coordinates and a laser beam flag indicating on oroff of the laser beam. The final coordinate flag may be written as dataof 15^(th) bit, where “1” is set if there are no data subsequent to theunit marking data D1, and the unit marking data D1 are final data,whereas “0” is set if there are some data subsequent to the unit markingdata D1, and the unit marking data D1 are not final data. The laser beamflag may be written as data of the 14^(th) bit, where “0” is set whenthe laser beam is turned off, whereas “1” is set when the laser beam isturned on. As described above, the control flag portion D1 c includesinstructions for a marking operation for marking each line component ofthe barcode and a jumping operation (non-emitting operation) for notconnecting line components while marking the line components.

The marking data generator section 30 transmits, on generating themarking data, the generated marking data to the control data generatorsection 40.

The control data generator section 40 moves the X-axis galvanometermirror 11 and the Y-axis galvanometer mirror 12 at respectivepredetermined speeds, turns the laser on or off at predeterminedtimings, and generates control data for altering the laser power atpredetermined timings based on the marking data. In order to move theX-axis galvanometer mirror 11 and the Y-axis galvanometer mirror 12 atconstant speeds, precise instructions may be required for moving thembetween coordinates of the marking data per speed timing; laser emittingtiming may be delayed based on the specified positions of the X-axisgalvanometer mirror 11 and Y-axis galvanometer mirror 12 in view ofpossible following delays of the X-axis galvanometer mirror 11 andY-axis galvanometer mirror 12, and a response characteristic of thelaser device 2. Further, the control data generator section 40 carriesout offset processing to move overall marking positions of the markingdata to appropriate positions on the rewritable medium 100. Note thatthe laser application device 1 includes standard values for a markingspeed or laser emitting timing; however, these values may be alteredfrom outside.

FIG. 9 is a diagram illustrating an example of a control data structurefor use in the marking control device 4 according to the firstembodiment.

The control data are values converted from the marking data in order toset the values in a later-described DA converter. The preparation ofsuch converted values may accelerate data output speeds. The controldata include plural unit control data D2. As illustrated in FIG. 9, theplural unit control data D2 include an X-output power portion D2 a, aY-output power portion D2 b, an output power setting portion D2 c, adata interval portion D2 d, and a control flag portion D2 e. TheX-output power portion D2 a is used for specifying a position controlvalue for the X-axis galvanometer mirror 11, the Y-output power portionD2 b is used for specifying a position control value for the Y-axisgalvanometer mirror 12, the output power setting portion D2 c is usedfor specifying an output power control value for output power of thelaser beam, and the data interval portion D2 d is used for writing aninterval between the current unit control data D2 and a subsequent unitcontrol data D2. The control flag portion D1 c includes a laser emittingflag, an X/Y output specifying flag, an output power specifying flag,and an end flag. The laser emitting flag may be written as data of15^(th) bit, where 1 is set when the laser beam is turned on. The X/Youtput specifying flag may be written as data of 14^(th) bit, where 1 isset when the position control values for the X-axis galvanometer mirror11 and the Y-axis galvanometer mirror 12 are output. The output powerspecifying flag may be written as data of 13^(th) bit, where 1 is setwhen the output power value of the laser beam is output. The end flagmay be written as data of 12^(th) bit, where 1 is set when the currentunit control data D2 is the final unit control data D2.

The control data generator section 40 transmits, on generating thecontrol data, the generated control data to the control data outputsection 50.

The control data output section 50 waits, on receiving a first unitcontrol data of the control data, until a marking start instruction isinput. Although the control data output section 50 may be configured tostart marking simultaneously upon receiving the unit control data, thecontrol data output section 50 basically starts marking after receivingthe marking start instruction signal from outside because the rewritablemedium 100 is moved by a separate device such as a conveyor controller.

When the control data output section 50 starts marking, the control dataoutput section 50 sets, immediately after reading the unit control data,respective data intervals in a CPU timer in the marking control device 4for generating timing for outputting the subsequent control data.Accordingly, output timing may be stabilized even if post-processingincludes timing differences. Next, the laser emitting flag value of theunit control data is output to the process, if the X/Y output specifyingflag is on, respective values of the X-output power portion D2 a and theY-output power portion D2 b of the unit control data are output to thegalvanometer mirror control signal generator section 60. If the outputpower specifying flag is on, the value of the output power settingportion D2 c is output to the laser emission control signal generatorsection 70. Thus, one cycle of outputting the control data is completed.Thereafter, the control data output section 50 repeats waiting for timerinterruption and outputting subsequent control data. When the end flagis on, the control data output section 50 ends marking.

The galvanometer mirror control signal generator section 60 includes twochannels of DA converters having 16-bit resolution. The DA convertersare connected to the respective X-axis servo driver 16 and Y-axis servodriver 17. The laser power control signal generator section 70 includesone channel of a DA converter having 16-bit resolution. The DA converteris connected to the laser device 2. The laser emission control signalgenerator section 80 is a binary digital signal port, and is connectedto the laser device 2.

As described above, the laser emitting section 90 includes the controldata generator section 40, the control data output section 50, thegalvanometer mirror control signal generator section 60, the laser powercontrol signal generator section 70, and the laser emission controlsignal generator section 80. The laser emitting section 90 drives theX-axis galvanometer mirror 11 and the Y-axis galvanometer mirror 12based on the marking data, and applies a laser beam to the rewritablemedium 100 based on the corresponding output power of the laser beam.

Accordingly, the laser application device 1 drives the X-axisgalvanometer mirror 11 and the Y-axis galvanometer mirror 12 based onthe marking data, and applies a laser beam to the rewritable medium 100,thereby marking the target image on the rewritable medium.

Next, a marking data generation process carried out by the markingcontrol device 4 according to the first embodiment is described.

FIG. 10 is a flowchart illustrating the marking data generation processcarried out by the marking control device 4 according to the firstembodiment.

The marking data generator section 30 determines positions (coordinatedata) of the plural line components of the barcode on the rewritablemedium 100 based on the marking instruction (step S1). Specifically,step S1 is carried out by the marking position determination section 31of the marking data generator section 30.

Next, the marking order determination section 30 determines the markingorder of the line components of the barcode (step S2). Specifically,step S2 is carried out by the marking order determination section 32 ofthe marking data generator section 30, and the marking orderdetermination section 32 determines the marking order of the plural linecomponents of the barcode for each line. In the marking control device 4according to the first embodiment, the marking order of line componentsfor each line is determined such that mutually adjacent lines are markedby reversing a marking direction of the current marking line from themarking direction of the adjacent line that has been marked immediatelybefore the current marking line. That is, the mutually adjacent linesare marked in the mutually opposite marking directions.

Note that the “mutually adjacent lines” are not only arranged adjacentto one another but they include overlapping portions of the adjacentlines.

The marking data generator section 30 adjusts output power of the laserbeam for marking the line components and sets on/off of the laser beam(step S3). Specifically, step S3 is carried out by the laser poweradjusting section 33 of the marking data generator section 30, and thelaser power adjusting section 33 determines (sets) the output power ofthe laser beam between a marking start position and a marking endposition of each line component of the barcode for each line.

In step S3, the same laser output power (e.g., rated power output) isset to mark from the marking start position to the marking end positionof a line component for a first line. However, from the second lineonward, a line component is divided into unit line components so thatthe laser output power may be increased per unit line component asmarking from the marking start position to the marking end position ofthe unit line components. For example, from the second line onward, ifone line component is divided into 10 unit line components, the laseroutput power may be set such that the laser output power is increased ina stepwise fashion by 820, 840, 860, 880, 900, 920, 940, 960, 980, and1000 in permillage for corresponding unit line components. That is, thelaser output power is set such that the laser output power at themarking start position is the maximum output power (rated power output)of the laser device 2 of 840/1000, and is increased in a stepwisefashion up to the maximum output power of 1000/1000 at the marking endposition.

As illustrated in FIG. 11, the settings of the above laser output powerare set by the laser power adjusting section that refers to data in atable having an identifier of each unit line component and the laseroutput power associated with the corresponding unit line component. Notethat in the data in FIG. 11, one line component is divided into 10 unitline components, and a serial number is given to each unit linecomponent from the marking start position to the marking end position ofthe line component.

Thus, in the first embodiment, from the second line onward, the laseroutput power applied to the rewritable medium 100 is increased for eachunit line component from the marking start position to the marking endposition of the line components for each line in a stepwise fashion.

Next, the marking data generator section 30 sets the marking speed ofeach line component of the barcode (step S4). Specifically, step S4 iscarried out by the marking speed adjusting section 34 of the markingdata generator section 30, and the marking speed adjusting section 34determines the marking speed from the marking start position to themarking end position of each line component for each line (i.e., oneline component including 10 unit line components obtained in step S3).In the first embodiment, the marking speed is set at 1000 in permillage.

Next, the marking data generator section 30 generates the marking data(step S5). Thus, the marking data illustrated in FIG. 8 are generatedper unit line component.

Next, the marking data generator section 30 determines whether themarking data have been generated for all the line components for alllines (step S6). That is, in step S6, whether the marking dataillustrated in FIG. 8 have been generated for all the unit linecomponents for all lines is determined.

In step S6, if the marking data generator section 30 determines that themarking data are not generated for all the line components for alllines, the marking data generator section 30 returns the current processto step S3. Thus, the processes between steps S3 and S6 are repeatedlycarried out so as to the laser output power and the marking speed areset for all the line components for all lines.

In step S6, if the marking data generator section 9 determines that themarking data are generated for all the line components for all lines,the generated marking data are converted into control data illustratedin FIG. 9, thereby carrying out marking operations.

FIGS. 12A, 12B, 12C are diagrams each illustrating a marking methodbased on the marking data generated by the marking control device 4according to the first embodiment. In the marking data generated by themarking control device 4 according to the first embodiment, the markingorder of line components for each line is determined such that mutuallyadjacent lines are marked by reversing a marking direction of thecurrent marking line from the marking direction of the adjacent linethat has been marked immediately before the current marking line.Accordingly, the mutually adjacent lines are marked in mutually opposite(reversed) marking directions based on the X-axis direction asillustrated by solid line arrows in FIG. 12A. That is, in the firstembodiment, the mutually adjacent lines of the target image are markedby reversing the marking directions from one to the other of theadjacent lines.

The solid line arrows in FIG. 12A indicate positions and directions formarking the line components. The origins of the solid line arrowsindicate the marking start positions, and the pointed ends of the solidline arrows indicate the marking end positions of the line components.In addition, broken line arrows in the Y-axis direction indicate jumping(non-emitting operations). Note that in the marking control device 4according to the first embodiment, no waiting time is inserted betweenmarking operations of the adjacent lines.

Note also that in the marking control device 4 according to the firstembodiment, the laser output power is constant while marking the linecomponent from the marking start position to the marking end positionfor the first line. However, from the second line onward, the laseroutput power is set such that the laser output power is increased forsucceeding unit line components in a stepwise fashion from the markingstart position to the marking end position of the line component foreach line. Accordingly, the thickness of the line component is increasedper unit line component in a stepwise fashion from the marking startposition to the marking end position of the line component for each lineas illustrated in FIG. 12B.

The above marking method is carried out by following a time chartillustrated in FIG. 12C. In FIG. 12C, a beam speed in an X-coordinatedirection indicates the marking speed in the X-axis direction. The beamspeed in the X-coordinate direction is set at the same speed andconstant with time for all the line components from the first to fifthlines. As illustrated in FIG. 12C, the beam speed in the X-coordinatedirection is 0 at intervals between the line components. The intervalsin which the beam speed in the X-coordinate direction is 0 correspond tojumping (non-emitting operations) intervals indicated by the broken linearrow in FIG. 12A.

The laser output power is constant (1000/1000) from the marking startposition to the marking end position of the line component for the firstline. However, the laser output power may be set such that the laseroutput power is increased for succeeding unit line components in astepwise fashion with time in a range of 820/1000 to 1000/1000, from themarking start position to the marking end position of each linecomponent for the second line to the fifth line.

The X-coordinate position and Y-coordinate position determined by theabove marking method are illustrated in FIG. 12C.

Referring to FIG. 12B, when marking of the line component of the firstline in a positive (+) direction of the X-axis direction is completed,the line component of the second line is marked in a negative (−)direction of the X-axis direction. At this moment, residual heatobtained by the laser beam application in the marking end position(right-hand end in the X-axis direction in FIG. 12B) of the linecomponent is higher than residual heat in the marking start position(left-hand end in the X-axis direction in FIG. 12B) of the linecomponent of the first line.

However, in the marking control device 4 according to the firstembodiment, when the line component of the second line (second linecomponent) is marked in the negative (−) direction of the X-axisdirection, the laser output power is increased for succeeding unit linecomponents in a stepwise fashion from the marking start position(right-hand end in the X-axis direction in FIG. 12B) to the marking endposition of the second line component (left-hand end in the X-axisdirection in FIG. 12B). Accordingly, thermal energy in the marking startposition and in the marking end position of the second line componentmay be congruent. Note that thermal energy in the marking start positionand in the marking end position of a corresponding line component may becongruent in the intervals between the line components of the second andthird lines, between the line components of the third and fourth lines,and between the line components of the fourth and fifth lines.

Accordingly, the above described color variability obtained in therelated art technologies illustrated in FIG. 3B may be controlled, sothat a target image area may be filled with solid color without colorvariability. Further, in the marking control device 4 according to thefirst embodiment, no waiting time is required between marking operationsof the line components of the adjacent lines, an overall time formarking the target image may be reduced. In the related art, the colorvariability is controlled by increasing the laser output power comparedto the ordinary laser output power. However, in the marking controldevice 4 according to the first embodiment, the maximum output (ratedpower output) of the laser device 2 may not need increasing.Accordingly, the rewritable medium 100 may not have locally accumulatedexcessive heat, which may decrease damage to the rewritable medium 100and increase the life-span of the rewritable medium 100.

As described above, in the marking control device 4 according to thefirst embodiment, when the mutually adjacent line are marked byreversing the marking direction of the current marking line from themarking direction of the adjacent line that has been marked immediatelybefore the current marking line, the laser output power is increased forsucceeding unit line components in a stepwise fashion from the markingstart position to the marking end position of the line component foreach line. Accordingly, color variability may be controlled and a targetimage area may be filled with solid color without color variability.Moreover, the overall marking time may be reduced and the life-span ofthe rewritable medium 100 may be increased.

Note that as described above, the laser output power is constant fromthe marking start position to the marking end position in marking theline component of the first line, and the laser output power isincreased in a stepwise fashion as marking from the marking startposition to the marking end position of the line components from thesecond line onward. However, due to properties of the laser power or therewritable medium 100, if the line component of the first line is markedwithout color variability by gradually increasing the laser output powerfrom the marking start position to the marking end position of the linecomponent, the laser output power may be set such that the laser outputpower is increased in a stepwise fashion from the marking start positionto the marking end position of the line component of the first line.

Further, in the marking control device 4 according to the firstembodiment, the ratio of the laser output power in the marking startposition to that in the marking end position of line components for thelines is 820/1000 from the second line onward. Such a ratio determinedbased on the result indicating that the laser output power in themarking start position is preferably approximately 80% of that in themarking end position in marking the line components of the lines fromthe second line onward. However, the laser output power in the markingstart position is not limited to the above value. The laser output powerin the marking start position may be set at an appropriate value basedon the rated power output of the laser device 2 or a thermal property ofthe rewritable medium 100.

Moreover, in the marking control device 4 according to the firstembodiment, a line component is divided into 10 unit line components foreach line, and the laser output power is set for succeeding unit linecomponents. However, the same laser output power may be set for thesuccessive unit line components of the line component.

Further, the number of unit line components is not limited to 10;however, the line component may be divided into any number of unit linecomponents. In addition, the line component for each line may not haveto be divided into plural unit line components, and the laser outputpower may be continuously increased from the marking start position tothe marking end position of an entire line component.

Further, in the marking control device 4 according to the firstembodiment, the (thermal) energy received by the rewritable medium 100is increased by increasing the laser output power in marking from themarking start position to the marking end position of the line componentfor each line. Alternatively, the (thermal) energy received by therewritable medium 100 may be increased by lowering the marking speed inmarking from the marking start position to the marking end position ofthe line component while the laser output power is made constant fromthe marking start position to the marking end position of the linecomponent for each line.

FIG. 13 is a diagram illustrating a marking method based on the markingdata generated by a modification of the marking control device 4according to the first embodiment.

In the marking method illustrated in FIG. 13, the marking speed isconstant (1000/1000 in permillage, 1000 is the same marking speedillustrated in FIG. 12 C) in marking the line component for the firstline; however, the marking speed is set such that the marking speed isgradually lowered in marking each line component from the marking startposition to the marking end position for the second line onward. Inaddition, the laser output power is set such that the laser output poweris constant in marking each line component from the marking startposition to the marking end position for the second line onward. Theabove settings may be implemented by preparing a table similar to thetable illustrated in FIG. 11. The table includes data of the markingspeed and the laser output power associated with the marking speed.Accordingly, above settings may be implemented by allowing the markingspeed adjusting section 34 of the marking data generator section 30 torefer to the table in marking each line component from the second lineonward. That is, each line component is divided into 10 unit linecomponents from the second line onward, and the marking speed may be setfor succeeding unit line components. The marking speed may be graduallyset at lower values for succeeding unit line components of the linecomponent in a stepwise fashion for each line from the second lineonward. For example, the marking speed adjusting section 34 of themarking data generator section 30 may refer to the table to set themarking speed such that when a standard value of the marking speed is1000 in permillage, the marking speed is decreased to 1180, 1160, 1140,1120, 1100, 1080, 1060, 1040, 1020, and 1000 for respective unit linecomponents in a stepwise fashion from the marking start position to themarking end position of each line component from the second line onward.Note that in the modification of the marking control device 4 accordingto the first embodiment illustrated in FIG. 13, the marking speedadjusting section 34 functions as an adjusting unit.

As described above, since the thermal energy on the rewritable medium100 may be made congruent from the marking start position to the markingend position of each line component by decreasing the making speed forcorresponding unit line components in a stepwise fashion whilemaintaining the laser output power constant, color variability may becontrolled, and the target image area may be filled with solid colorwithout color variability. Further, in the marking control device 4according to the first embodiment, no waiting time is required betweenmarking operations of the line components of the adjacent lines, so thatan overall time for marking the target image may be reduced. Inaddition, in the marking control device 4 according to the firstembodiment, since the target image may be drawn without increasing themaximum power of the laser output power, the rewritable medium 100 maynot locally accumulate excessive heat, thereby increasing the life-spanof the rewritable medium 100.

Second Embodiment

FIG. 14 is a configuration block diagram illustrating a marking controldevice 204 according to a second embodiment.

The marking control device 204 according to the second embodimentdiffers from the marking control device 4 according to the firstembodiment in that the marking data generator section 30 of the markingcontrol device 204 according to the second embodiment includes a markingposition alteration section 235. Since the components of the markingcontrol device 204 according to the second embodiment other than markingthe position alteration section 235 are the same as those of the markingcontrol device 4 according to the first embodiment, their descriptionsare omitted by assigning the same reference numerals to the componentssame as those of the marking control device 4 according to the firstembodiment.

FIGS. 15A, 15B, 15C are diagrams each illustrating a marking methodbased on marking data generated by the marking control device 204according to the second embodiment.

In the marking method carried out by the marking control device 204according to the second embodiment, each line component of each line isdivided into a predetermined number of unit line components (10 unitline components in this case) from the second line onward, and the laseroutput power is increased for succeeding unit line components from themarking start position to the marking end position of the line componentin a stepwise fashion in the same manner as the marking method carriedout by the marking control device 4 according to the first embodiment.Note that similar to the first embodiment, the origins of the solid linearrows indicate the marking start positions, and the pointed ends of thesolid line arrows indicate the marking end positions of the linecomponents in FIG. 15A.

As illustrated in FIG. 15A, in the marking control device 204 accordingto the second embodiment, line components from the second line onwardare marked by moving (shifting) the marking start position of each linecomponent in the negative (−) direction of the Y-axis direction. Themarking start position of each line is altered by the marking positionalteration section 235. Specifically, the marking position alterationsection 235 alters a Y-coordinate value of the marking start position ofeach line component contained in the marking data.

The reason for altering the marking start position of the linecomponents from the second line onward is that the residual heat in therewritable medium 100 after the preceding line component is marked ishigher in the marking start position than in the marking end position ofthe subsequent line component from the second line onward. Thus, anamount of heat received in overlapping portions or peripheral portionsof the adjacent line components in the rewritable medium 100 may bebalanced by locating the marking start position of a subsequent linecomponent away from the marking start position of a preceding linecomponent.

A shifting (moving) amount of each line component in the negative (−)direction of the Y-axis direction from the second line onward ispreferably in a range of ⅙ to ⅔ of a width (in the Y-axis direction) ofthe line component.

FIG. 16 is a flowchart illustrating a marking data generation processcarried out by the marking control device 204 according to the secondembodiment.

Note that steps S201 and S202 in FIG. 16 are identical to steps S1 andS2 in FIG. 10. When the marking order is determined in step S202, themarking data generator section 30 alters coordinates of the markingstart position of each line component for the second line onward (stepS203). Specifically, step S203 is carried out by the marking positionalteration section 235 of the marking data generator section 30, and themarking position alteration section 235 locates the marking startposition of the subsequent line component away from the marking startposition of the preceding line component for each line from the secondline onward as described with reference to FIG. 15.

When the marking start position of the subsequent line component, isaltered in step S203, the marking data generator section 230 advancesthe current process to step S204. Steps S204 through S208 are basicallythe same as steps S3 through S7; however, the Y-coordinate values of theline components altered by the marking position alteration section 235from the second line onward contained in the marking data generated instep S206 differ from the Y-coordinate values of the line componentsfrom the second line onward contained in the marking data of the firstembodiment.

When steps S204 through S207 are repeatedly conducted, and the laseroutput power and the marking speed are set for all the line componentsfor all lines, the generated marking data are converted into controldata (see FIG. 9) to carry out marking operations.

As described above, in the marking control device 204 according to thesecond embodiment, when the mutually adjacent lines are marked byreversing the marking direction of the current marking line from themarking direction of the adjacent line that has been marked immediatelybefore the current marking line, the laser output power is increasedfrom the marking start position to the marking end position of the linecomponent in a stepwise fashion for each line, and the marking startposition of the subsequent line component is located away from themarking start position of the preceding line component line by line byaltering coordinate values of the marking start position of thesubsequent line components from the second line onward.

Accordingly, thermal energy on the rewritable medium 100 may be madecongruent in the overlapping portions and peripheral portions of themutually adjacent line components. As a result, color variability may becontrolled, and the target image area may be filled with solid colorwithout color variability. Further, in the marking control device 204according to the second embodiment, no waiting time is required betweenmarking operations of the line components of the adjacent lines, anoverall time for marking the target image may be reduced. Moreover, thelife-span of the rewritable medium 100 may be increased.

Note that as described above, from the second line onward, the markingstart position of each line component is shifted in the negative (−)direction of the Y-axis direction (to be located away from the markingstart position of the preceding line component). However, the markingend position of each line component may also be shifted from the secondline onward in addition to the shifting of the marking start position ofeach line component in the negative (−) direction of the Y-axisdirection from the second line onward. That is, the marking end positionof each line component may also be shifted in the positive (+) directionof the Y-axis direction from the second line onward, in addition to theshifting of the marking start position of each line component in thenegative (−) direction of the Y-axis direction from the second lineonward. The marking start position and the marking end position of eachline component may be altered by selecting appropriate values for thecoordinates of the marking start position and the coordinates of themarking end position of each line component based on the laser outputpower of the laser device 2 or the thermal property of the rewritablemedium 100.

Note that in the first and second embodiments, the target image is thebarcode. However, the target image marked by the marking devicecontrolled by the marking control device 4 or 204 according to acorresponding one of the first embodiment and the second embodiment isnot limited to the barcode, but may be any marks including characters,numbers, symbols, and graphics.

Note that a computer program to be executed by the laser applicationdevice 1 according to the first embodiment or the second embodiment maybe provided as installable or executable formatted files recorded on acomputer-readable recording medium such as a CD-ROM, flexible disk (FD),CD-R, DVD (Digital Versatile Disk), and the like.

Alternatively, the computer program to be executed by the laserapplication device 1 according to the first embodiment or the secondembodiment may be stored in a computer connected over the network suchas the Internet, and the stored computer program may be downloaded fromthe computer over the network. Further, the computer program to beexecuted by the laser application device 1 according to the firstembodiment or the second embodiment may be provided or distributed viathe network such as the Internet.

Next, marking control methods according to a third embodiment and afourth embodiment are described.

[Marking Control Method]

The marking control method according to the third embodiment or thefourth embodiment includes one of an image recording process and animage erasing process. Note that the marking control method according tothe third embodiment or the fourth embodiment is not particularlylimited to marking on the reversible recording medium and may beappropriately selected based on various purposes. For example, themarking control method may be utilized as a method for marking an imageon a non-reversible recording medium. However, it is preferable that themarking control method according to the third embodiment or the fourthembodiment be utilized as a marking control method for recording orerasing an image on a thermoreversible recording medium.

<Image Recording Process>

In the image recording process, the thermoreversible recording medium isirradiated with a laser beam, and heated laser beam lines are coloredand marked on the thermoreversible recording medium, thereby forming animage (i.e., a target image).

In the image recording process, a lower limit of the laser output poweris not particularly limited, and may be appropriately selected based onvarious purposes. However, the lower limit of the laser output power maybe preferably 1 W or higher, more preferably 3 W or higher, andparticularly preferably 5 W or higher.

If the lower limit of the laser output power is lower than 1 W, imagerecording time may be increased. Accordingly, the laser may not haveenough output power for reducing the image recording time.

Likewise, an upper limit of the laser output power is not particularlylimited, and may be appropriately selected based on various purposes.However, the upper limit of the laser output power may be preferably 200W or lower, more preferably 150 W or lower, and particularly preferably100 W or lower. If the laser output power exceeds 200 W, the size of thelaser device may be increased.

In the image recording process, a lower limit of a scanning speed of thelaser beam applied to the thermoreversible recording medium is notparticularly limited, and may be appropriately selected based on variouspurposes. However, the lower limit of the scanning speed of the laserbeam may be preferably 300 mm/s or higher, more preferably 500 mm/s orhigher, and particularly preferably 700 mm/s or higher.

If the scanning speed of the laser beam is lower than 300 mm/s, theimage recording time may be increased.

Likewise, an upper limit of the scanning speed of the laser beam appliedto the thermoreversible recording medium is not particularly limited,and may be appropriately selected based on various purposes. However,the upper limit of the scanning speed of the laser beam may bepreferably 15,000 mm/s or lower, more preferably 10,000 mm/s or lower,and particularly preferably 8,000 mm/s or lower.

If the scanning speed of the laser beam exceeds 15,000 mm/s, an imagemay not be uniformly formed on the thermoreversible recording medium.

In the image recording process, a lower limit of a spot diameter of thelaser beam applied to the thermoreversible recording medium is notparticularly limited, and may be appropriately selected based on variouspurposes. However, the lower limit of the spot diameter of the laserbeam may be preferably 0.02 mm or more, more preferably 0.1 mm or more,and particularly preferably 0.15 mm or more.

Likewise, an upper limit of the spot diameter of the laser beam appliedto the thermoreversible recording medium is not particularly limited,and may be appropriately selected based on various purposes. However,the upper limit of the spot diameter of the laser beam may be preferably3.0 mm or less, more preferably 2.5 mm or less, and particularlypreferably 2.0 mm or less.

If the spot diameter of the laser beam is less than 0.02 mm, a linewidth of the image may be too thin, thereby decreasing viewability ofthe image. By contrast, if the spot diameter of the laser beam exceeds3.0 mm, the line width of the image may be too thick, thereby causingadjacent lines to mutually overlap. Accordingly, small sized images maynot be formed (recorded) on the thermoreversible recording medium.

In the image recording process, a laser light source of the laser beamapplied is not particularly limited, and may be appropriately selectedbased on various purposes. However, the laser light source of the laserbeam may preferably be at least one of YAG laser light, fiber laserlight, and semiconductor laser (i.e., a laser diode, LD) light.

<Image Erasing Process>

In the image erasing process, the thermoreversible recording medium isirradiated with a laser beam, and heated laser beam lines forming theimage are decolored on the thermoreversible recording medium, therebyerasing the image.

In the image erasing process, a lower limit of the laser output power isnot particularly limited, and may be appropriately selected based onvarious purposes. However, the lower limit of the laser output power maybe preferably 5 W or higher, more preferably 7 W or higher, andparticularly preferably 10 W or higher.

If the lower limit of the laser output power is lower than 5 W, imageerasing time may be increased. Accordingly, the laser may not haveenough output power for reducing the image erasing time, therebyexhibiting insufficient erasure of the image.

Likewise, an upper limit of the laser output power is not particularlylimited, and may be appropriately selected based on various purposes.However, the upper limit of the laser output power may be preferably 200W or lower, more preferably 150 W or lower, and particularly preferably100 W or lower. If the laser output power exceeds 200 W, the size of thelaser device may be increased.

In the image erasing process, a lower limit of a scanning speed of thelaser beam applied to the thermoreversible recording medium is notparticularly limited, and may be appropriately selected based on variouspurposes. However, the lower limit of scanning speed of the laser beammay be preferably 100 mm/s or higher, more preferably 200 mm/s orhigher, and particularly preferably 300 mm/s or higher.

If the scanning speed of the laser beam is lower than 100 mm/s, theimage erasing time may be increased.

Likewise, an upper limit of the scanning speed of the laser beam appliedto the thermoreversible recording medium is not particularly limited,and may be appropriately selected based on various purposes. However,the upper limit of the scanning speed of the laser beam may bepreferably 20,000 mm/s or lower, more preferably 15,000 mm/s or lower,and particularly preferably 10,000 mm/s or lower.

If the scanning speed of the laser beam exceeds 20,000 mm/s, an imagemay not be uniformly erased from the thermoreversible recording medium.

In the image erasing process where the image formed on thethermoreversible recording medium is decolored by heating with the laserbeam application, a lower limit of a spot diameter of the laser beamapplied to the thermoreversible recording medium is not particularlylimited, and may be appropriately selected based on various purposes.However, the lower limit of the spot diameter of the laser beam may bepreferably 0.5 mm or more, more preferably 1.0 mm or more, andparticularly preferably 2.0 mm or more. Likewise, an upper limit of thespot diameter of the laser beam applied to the thermoreversiblerecording medium is not particularly limited, and may be appropriatelyselected based on various purposes. However, the upper limit of the spotdiameter of the laser beam may be preferably 14.0 mm or less, morepreferably 10.0 mm or less, and particularly preferably 7.0 mm or less.

If the spot diameter of the laser beam is less than 0.5 mm, the imageerasing time may be increased. By contrast, if the spot diameter of thelaser beam exceeds 14.0 mm, the laser may not have enough output powerfor reducing the image erasing time, thereby exhibiting insufficienterasure of the image.

In the image erasing process, the laser light source of the laser beamapplied is not particularly limited, and may be appropriately selectedbased on various purposes. However, the laser light source of the laserbeam may preferably be at least one of YAG laser light, fiber laserlight, and semiconductor laser (i.e., a laser diode, LD) light.

In the image recording process and the image erasing process, awavelength of the laser beam may be preferably 700 nm or more, morepreferably 720 nm or more, and particularly preferably 750 nm or more.An upper limit of the wavelength of the laser beam applied to thethermoreversible recording medium is not particularly limited, and maybe appropriately selected based on various purposes. However, the upperlimit of the wavelength of the laser beam may be preferably 1,500 nm orless, more preferably 1,300 nm or less, and particularly preferably1,200 nm or less.

If the wavelength of the laser beam is shorter than 700 nm, the contrastof the image in a visible light region may be lowered while recordingthe image or other regions of the thermoreversible recording medium maybe colored. In an ultraviolet light region having a wavelength furthershorter than the 700 nm of the visible light region, thethermoreversible recording medium may be deteriorated. Moreover, aphotothermal conversion material added to the thermoreversible recordingmedium may require high decomposition temperature for obtainingdurability for repeated image processing. However, if the photothermalconversion material needs to contain an organic dye, it may be difficultto obtain a photothermal conversion material having a long absorptionwavelength and having high decomposition temperature. Thus, thewavelength of the laser beam may be preferably 1,500 nm or less.

In the marking control method according to the embodiments, at least oneof the image recording process and the image erasing process includes afirst laser beam marking line that is marked from the first startingpoint to the first ending point, and a second laser beam marking linethat is marked adjacent to the first laser beam marking line by applyinga laser beam from a second starting point to a second ending point suchthat the second ending point of the second laser beam marking line islocated in a line slanted toward the first starting point of the firstlaser beam marking line based on a line in parallel with the first laserbeam marking line.

The marking control method is not particularly limited and appropriatelyselected based on various purposes. However, it is preferable that athird laser beam marking line be marked adjacent to the second laserbeam marking line immediately after marking of the second laser beammarking line, by applying a laser beam from a third starting point to athird ending point such that the third ending point of the third laserbeam marking line is located in a line slanted toward the secondstarting point of the second laser beam marking line based on a line inparallel with the second laser beam marking line.

With this method, the effect of the accumulated heat generated byscanning the third starting point of the third laser beam marking lineimmediately after the scanning of the second ending point of the secondlaser beam marking line may be reduced in a turning portion between thesecond ending point of the second laser beam marking line and the thirdstarting point of the third laser beam marking line.

The marking method for the third laser beam marking line may not beparticularly limited; however, the third laser beam marking line maypreferably be marked in parallel with the first laser beam marking line.

With this method, the image may be recorded or erased without densityvariability in the image recording area and the solidly filled imagemarking area of the thermoreversible recording medium.

Note that the term “parallel” includes the meanings of both “preciselyparallel” and “approximately parallel” based on the performance of theimage processing.

The above marking method includes marking of the slanted line; however,the marking method may also include marking of a line partially inparallel with the adjacent line in the same direction. That is, if asolidly filled image is filled with the even number of marking lines,the last slanted marking line may make the entire image slanted.Accordingly, when the solidly filled image is filled with the evennumber of marking lines, it is preferable that one of the marking linesbe in parallel with one of the preceding marking lines.

Further, the starting point and the ending point are, unless otherwisespecified, the starting point and the ending point of the continuousmarking line. However, if the continuous marking line includes theturning portion, the turning portion of the continuous marking line mayinclude the starting point and the ending point.

The marking control method is not particularly limited, and may beappropriately selected based on various purposes. However, in themarking control method, it is preferable that a laser beam not beapplied to an interval between an ending point of a first laser beammarking line and a starting point of a second laser beam marking lineadjacent to the first laser beam marking line.

With this method, the laser scanning time may be short, the solidlyfilled image may be recorded on or erased from the thermoreversiblerecording medium in a short time, and heat may not be accumulated in theturning portion of the laser beam marking line.

Further, it is preferable that the starting point of the second laserbeam marking line be marked in a line perpendicular to the first laserbeam marking line from the end point of the first laser beam markingline.

With this method, the solidly filled image may be formed in arectangular image cell without density variability, and the printingrecord may be efficiently carried out. Further, the printed record imagemay also be efficiently decolored or erased.

Further, the marking control method is not particularly limited;however, it is preferable that irradiation energy of the laser beam thatscans the first laser beam marking line be higher than irradiationenergy of the laser beam that scans the second laser beam marking line.

In this case, the first laser beam marking line is initially marked inthe target image (image) area to be marked, and the second laser beammarking line may be marked by utilizing the accumulated heat generatedby marking of the first laser beam marking line. Accordingly, excessiveenergy transmission on the thermoreversible recording medium may besuppressed by marking the first laser beam marking line with energyhigher than that of the second laser beam marking line, and marking thesecond laser beam marking line with energy lower than that of the firstlaser beam marking line.

In the following, details of the third embodiment and the fourthembodiment are described with reference to FIGS. 5A and 5B.

FIG. 5A is a diagram illustrating a laser beam scanning method forrecording or erasing the image according to the third embodiment. Asillustrated in FIG. 5A, with the laser beam scanning method according tothe third embodiment, the laser beam is scanned such that the secondlaser beam marking line 452 is slanted toward the first laser beammarking line 451, unlike the laser beam scanning method in FIG. 4A,where the laser beam is scanned such that the second laser beam markingline 412 is marked in parallel with the first laser beam marking line411. That is, with the laser beam scanning method according to the thirdembodiment, the marking position of the second laser beam marking line452 is adjusted such that a first distance between the ending point ofthe first laser beam marking line 451 and the starting point of thesecond laser beam marking line 452 is longer than a second distancebetween the starting point of the first laser beam marking line 451 andthe ending point of the second laser beam marking line 452.

The configuration in which the second laser beam marking line 452 isslanted toward the first laser beam marking line 451 is illustrated inFIG. 5A, where a ratio of a slanted amount to a pitch width is 0.1 ormore (i.e., slanted amount/a pitch width≧0.1).

The ratio of the slanted amount to the pitch width is not particularlylimited insofar as the ratio is 0.1 or more, and may be appropriatelyselected based on various purposes. However, if the ratio of the slantedamount to the pitch width is small, the adverse effect due to theaccumulated heat may not be sufficiently suppressed, and if the ratio ofthe slanted amount to the pitch width is too large, energy applied tothe thermoreversible recording medium may not be sufficient.Accordingly, it is preferable that the ratio of the slanted amount tothe pitch width be in a range of 0.2 to 0.8.

The pitch amount indicates a shortest distance between the central pointin the longitudinal direction of the second laser beam marking line 452and the first laser beam marking line 451.

The slanted amount indicates a shortest distance between the centralpoint in the longitudinal direction of the second laser beam markingline 452 and a line extending in parallel with the first laser beammarking line 451 from the starting point of the second laser beammarking line 452.

With this marking control method according to the third embodiment, thelaser scanning time may be short, the solidly filled image may berecorded on or erased from the thermoreversible recording medium in ashort time, and heat may not be accumulated in the turning portion ofthe laser beam marking line. Note that the turning portion of the laserbeam is obtained by scanning the second laser beam marking line 452immediately after the scanning of the first laser beam marking line 451.

FIG. 5B is a diagram illustrating a laser beam scanning method forrecording or erasing the image according to the fourth embodiment. Asillustrated in FIG. 5B, with the laser beam scanning method according tothe fourth embodiment, the laser beam is scanned such that the secondlaser beam marking line 452 is marked to be slanted toward the firstlaser beam marking line 451, unlike the laser beam scanning method inFIG. 4B, where the laser beam is scanned such that the second laser beammarking line 422 is marked in parallel with the first laser beam markingline 421.

With this marking control method according to the fourth embodiment,since the laser beam is not applied to a region corresponding to aturning portion between the first ending point to the second startingpoint, excessive application of energy on the thermoreversible recordingmedium obtained due to decreased marking speed in marking of the turningportion may be prevented. Thus, the marking control method according tothe fourth embodiment is particularly preferable because the methodprovides the effect of preventing excessive energy application inaddition to the effect obtained by the marking control method accordingto the third embodiment.

Note that the marking control method according to the fourth embodimentincludes the same processes except the process where the laser beam isnot applied to the region corresponding to the turning portion betweenthe first ending point to the second starting point. Accordingly, thedescription of the marking control method according to the thirdembodiment may also be applied as that of the marking control methodaccording to the fourth embodiment.

<Thermoreversible Recording Medium>

A thermoreversible recording medium is configured to change transparencyor color based on temperature.

The thermoreversible recording medium used in the embodiments is notparticularly limited. An example of the thermoreversible recordingmedium includes: a first thermoreversible recording layer and a secondthermoreversible recording layer provided in this order, and mayoptionally include other layers such as a first oxygen barrier layer, asecond oxygen barrier layer, an ultraviolet (UV) absorber layer, abacking layer, a protection layer, an intermediate layer, an undercoatlayer, an adhesive layer, a cohesion layer, a coloring layer, an airspace, and a light reflection layer. The above layers may be a singlelayer structure or a multilayer structure. Note that a layer provided onthe photothermal conversion layer is preferably formed of a materialthat absorbs a small amount of a laser beam having a specific wavelength so as to reduce a loss of energy of the laser beam having thespecific wavelength applied on the layer of the thermoreversiblerecording medium.

As illustrated in FIG. 17A, a thermoreversible recording medium 500 mayinclude a supporting member 501, and plural layers including a firstthermoreversible recording layer 502, a photothermal conversion layer503, and a second thermoreversible recording layer 504. The above plurallayers are provided in that order on the supporting member 501.

Alternatively, as illustrated in FIG. 17B, the thermoreversiblerecording medium 500 may include the supporting member 501, and plurallayers including a first oxygen barrier layer 505, the firstthermoreversible recording layer 502, the photothermal conversion layer503, the second thermoreversible recording layer 504, and a secondoxygen barrier layer 506. The above plural layers are provided in thatorder on the supporting member 501.

Further, as illustrated in FIG. 17C, the thermoreversible recordingmedium 500 may include the supporting member 501, and plural layersincluding the first oxygen barrier layer 505, the first thermoreversiblerecording layer 502, the photothermal conversion layer 503, the secondthermoreversible recording layer 504, an ultraviolet absorber layer 507,and the second oxygen barrier layer 506. The above plural layers areprovided in that order on the supporting member 501. In addition, thethermoreversible recording medium 500 may include a backing layer 508provided on a side of the supporting member 501 where the firstthermoreversible recording layer 502 and the second thermoreversiblerecording layer 504 are not provided.

Note that although not illustrated in FIGS. 17A, 17B, and 17C, aprotection layer may be provided as an uppermost layer of thethermoreversible recording medium 500; that is, the protection layer maybe provided on the second thermoreversible recording layer 504 in FIG.17A, on the second oxygen barrier layer 506 in FIG. 17B, or on thesecond oxygen barrier layer 506 in FIG. 17C.

—Supporting Member—

A shape, a structure, a size and the like of the supporting member usedin the embodiments are not particularly limited, and may beappropriately selected based on various purposes. However, thesupporting member may have a tabular shape, a single layer structure ora multilayer structure, and an appropriate size determined based on thesize of the thermoreversible recording medium.

The supporting member may be made of an inorganic material or an organicmaterial.

Examples of the inorganic material include glass, quartz, silicon, oxidesilicon, aluminum oxide, SiO₂, and metal.

Examples of the organic material include paper, cellulose derivativessuch as cellulose triacetate, synthetic paper, and films such aspolyethylene terephthalate, polycarbonate, polystyrene, and polymethylmethacrylate.

The above inorganic material and the organic material may be used aloneor may be used in combination of two or more. Among these, the organicmaterial may be preferable, where the films such as polyethyleneterephthalate, polycarbonate, and polymethyl methacrylate arepreferable, and the polyethylene terephthalate is particularlypreferable.

It is preferable that the supporting member be surface modified bycorona discharge, oxidation reaction (chromic acid), etching,tackiness-improving treatment, and antistatic treatment.

It is also preferable that the supporting member be white color byadding white pigment such as titanium oxide.

A thickness of the supporting member is not particularly limited, andmay be appropriately selected based on various purposes. However, thethickness of the supporting member may be preferably in a range of 10 to2,000 μm, and more preferably 50 to 1,000 μm.

—First Thermoreversible Recording Layer and Second ThermoreversibleRecording Layer—

The first thermoreversible recording layer and the secondthermoreversible recording layer (hereinafter simply called a“thermoreversible recording layer”) include an electron-donatingcolor-developing compound of leuco dye, and an electron acceptingcompound of a developer. The thermoreversible recording layer furtherincludes binder resin and optionally includes other components. Thethermoreversible recording layer is configured to reversibly change itscolor by the application of heat.

The electron-donating color-developing leuco dye reversibly changing thecolor with heat, and the electron accepting developer are materialscapable of reversibly generating visible changes based on temperaturechange. Specifically, the leuco dye and the developer are capable ofchanging color between relatively colored or relatively decolored statesbased on the difference in the heating temperature and the cooling speedafter heating.

—Leuco Dye—

The leuco dye is colorless or pale dye precursor. The leuco dyes are notparticularly limited, and may be selected from known compounds based onvarious purposes. Preferable examples of the leuco dye includetriphenylmethanephthalide leuco compounds, triallylmethane leucocompounds, fluoran leuco compounds, phenothiazine leuco compounds,thiofluoran leuco compounds, xanthene leuco compounds, indophthalylleuco compounds, spiropyran leuco compounds, azaphthalide leucocompounds, chromenopyrazole leuco compounds, methine leuco compounds,rhodamineanilinolactam leuco compounds, rhodaminelactam leuco compounds,quinazoline leuco compounds, diazaxanthene leuco compounds, andbislactone leuco compounds. Among these, fluoran leuco compounds orphthalide leuco compounds are particularly preferable due to theirexcellent coloring/decoloring properties, excellent psychophysical colorproperties, and excellent storage stability. The above leuco dyecompounds may be used alone or in combination of two or more. Thethermoreversible recording layer may develop (form) multiple colors orfull-color by laminating layers mutually developing different colors.

—Reversible Developer—

The reversible developer used in the embodiments is not particularlylimited insofar as coloring and decoloring are reversibly carried withheat, and may be selected from known compounds for various purposes.Preferable examples of the reversible developer includes compoundshaving at least one of the following structures in molecules selectedfrom (1) a structure having a color-developing ability to cause theleuco dye to develop color (e.g., phenolic hydroxyl group, carboxylicacid group, and phosphate group); and (2) a structure capable ofcontrolling intermolecular cohesion (e.g., long-chain hydrocarbon grouplinking structure). Note that the long-chain hydrocarbon group linkingstructure may include linking group having divalent or more heteroatoms,or the long-chain hydrocarbon group may include at least one of thelinking group and an aromatic group.

As the structure (1) having the color-developing ability to cause theleuco dye to develop color, phenol is preferable.

As the structure (2) capable of controlling intermolecular cohesion, thelong-chain hydrocarbon group having 8 carbon atoms may be preferable.The number of carbon atoms of the long-chain hydrocarbon group may bemore preferably 11 or more, and the upper limit of the number of thecarbon atoms may be preferably 40 or less, and more preferably 30 orless.

Among the reversible developers, a phenol compound represented by thegeneral formula (1) is preferable, and a phenol compound represented bythe general formula (2) is more preferable.

In the general formulas (1) and (2), R¹ represents a single bond or analiphatic hydrocarbon group having 1 to 24 carbon atoms. R² representsan aliphatic hydrocarbon group having 2 or more carbon atoms that mayinclude a substituent, and the aliphatic hydrocarbon group maypreferably include 5 or more carbon atoms, and more preferably 10 ormore carbon atoms. R³ represents an aliphatic hydrocarbon group having 1to 35 carbon atoms, and may preferably include 6 to 35 carbon atoms, andmore preferably 8 to 35 carbon atoms. The above aliphatic hydrocarbongroups may be contained alone or may be contained in combination of twoor more.

The sum of carbon atoms in R¹, R², and R³ is not particularly limited,and may be appropriately selected based on various purposes. However,the sum of carbon atoms in R¹, R², and R³ may be preferably 8 or more,and more preferably 11 or more. The upper limit of the sum of carbonatoms in R¹, R², and R³ is preferably 40 or less, and more preferably 35or less.

If the sum of the carbon atoms is less than 8, coloring stability orerasability may be lowered.

The aliphatic hydrocarbon groups may include straight-chains,branched-chains, or unsaturated bonds; however, it is preferable thatthe aliphatic hydrocarbon groups include straight-chains. Further,examples of the substituent bonded with the hydrocarbon groups include ahydroxyl group, halogen atoms, and an alkoxy group.

X and Y may be the same or different, and may represent a divalent groupof N or O atoms. Specific examples of the divalent group include oxygenatoms, an amide group, a urea group, a diacylhydrazine group, an oxamidegroup, and an acyl urea group. Among these, the amide group and ureagroup are preferable.

In the general formulas (1), and (2), n represents integers from 0 to 1.

It is preferable that the electron-accepting compound (developer) becombined with a compound having in the molecules at least one of a—NHCO-group and an —OCONH-group, because an intermolecular interactionbetween a decoloring accelerator and the developer may be induced duringthe decoloring process to improve the coloring/decoloring properties.

The decoloring accelerator is not particularly specified and may beappropriately selected based on various purposes.

The thermoreversible recording layer may include binder resin, and mayoptionally include various additives in order to improve or controlcoating properties or coloring/decoloring properties of thethermoreversible recording medium. Examples of the additives includesurfacants, electro-conductive agents, fillers, antioxidants, opticalstabilizers, color stabilizers, and decoloring accelerators.

—Binder Resin—

The binder resin is not particularly specified insofar as the binderresin is capable of binding the thermoreversible recording layer, andmay be appropriately selected based on various purposes. The binderresin may be prepared by mixing one or more resins selected from theknown resins. Among the know resins, resin that is curable by theapplication of heat, UV rays, and electron beams is preferable in orderto improve durability for repeated use, and thermosetting resin havingisocyanate compounds as crosslinking agents may be particularlypreferable. Examples of the thermosetting resin include resin reactivewith a hydroxyl group or a carboxyl group, or resin copolymerized withmonomers having a hydroxy group or a carboxyl group or with othermonomers. Specific examples of the thermosetting resin include phenoxyresin, polyvinyl butyral resin, cellulose acetate propionate resin,cellulose acetate butyral resin, acrylic polyol resin, polyester polyolresin, and polyurethane polyol resin. Among these, the acrylic polyolresin, polyester polyol resin, and polyurethane polyol resin areparticularly preferable.

The mixing ratio (mass ratio) of the binder resin to a color developeris preferably 0.1 to 10 in the thermoreversible recording layer when thecolor developer is 1. If the amount of the binder resin is too small,heat resistance of the thermoreversible recording layer may not besufficient, whereas if the amount of the binder resin is too large,coloring density may be reduced.

The crosslinking agent is not particularly specified and may beappropriately selected based on various purposes. Preferable examples ofthe crosslinking agent include isocyanates, amino resins, phenol resins,amine resins, and epoxy compounds. Among these, the isocyanates may bepreferable, and polyisocyanate compounds having plural isocyanate groupsmay be particularly preferable.

The amount of the crosslinking agent added to the binder resin is notparticularly specified; however, the ratio of a functional group of thecrosslinking agent to an active group of the binder resin may bepreferably 0.01 to 2. If the ratio is 0.01 or less, the heat resistancemay be insufficient, and if the ratio is 2 or more, coloring/decoloringproperties may be adversely affected.

Further, catalyst may be added to the binder resin as a crosslinkingagent accelerator used for the above reaction.

Gel fraction (i.e., degrees of cross-linkage) in crosslinked binderresin is not particularly limited, and may be preferably 30% or more,more preferably 50% or more, and particularly preferably 70% or more. Ifthe gel fraction is less than 30%, the cross-linkage may beinsufficient, thereby lowering the durability.

Whether the binder resin is crosslinked or not may be identified byimmersing the film (layer) in a highly-solvating solvent. Specifically,with uncrosslinked binder resin, since the binder resin dissolves in thesolvent, the resin does not visibly remain as a solute.

Other components of the thermoreversible recording layer are notparticularly specified and may be appropriately selected based onvarious purposes. Preferable examples of the crosslinking agent includesurgacants and plasticizer for facilitating recording of images.

Any known solvents, dispersing devices, coating methods, anddrying-curing methods may be used may be used for forming thethermoreversible recording layer.

Note that materials of the coating liquid for the thermoreversiblerecording layer may simultaneously be dispersed in the solvent using thedispersing device, or individually dispersed in the solvent. Further,the materials of the coating liquid for the thermoreversible recordinglayer may be precipitated by rapid cooling or slow cooling.

A method for forming the thermoreversible recording medium is notparticularly specified, and may be appropriately selected based onvarious purposes. However, the following three methods may bepreferable.

(1) The above resin, the leuco dyes, and the reversible developer aredissolved or dispersed in the solvent to prepare the coating liquid forthe thermoreversible recording layer, and the coated supporting memberis then crosslinked simultaneously with or after drying the solvent ofthe coating liquid to form a coating sheet.

(2) The above resin is dissolved in the solvent, the leuco dyes, and thereversible developer are then dispersed in the resin-dissolved solventto prepare the coating liquid for the thermoreversible recording layer,the coating liquid is applied on the supporting member, and the coatedsupporting member is then crosslinked simultaneously with or afterdrying the solvent of the coating liquid to form a coating sheet.

(3) The above resin, the leuco dyes, and the reversible developer aremutually mixed by hot-melting treatment without the solvent, thehot-melted mixture is formed in a sheet, the sheet is cooled, and thecooled sheet is then crosslinked. Note that the thermoreversiblerecording layer may be prepared without using the supporting member as asheet-like thermoreversible recording medium.

The solvent used in the above methods (1) and (2) may vary with types ofthe resin, the leuco dye, and the developer and are not particularlyspecified; however, preferable examples of the solvent includetetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone,chloroform, carbon tetrachloride, ethanol, toluene, and benzene.

Note that the reversible developer is dispersed as particles in thethermoreversible recording layer.

The coating liquid for the thermoreversible recording layer may includevarious pigments, antifoaming agents, dispersants, slipping agents,preservatives, crosslinking agents, and plasticizer.

The coating method of the thermoreversible recording medium is notparticularly specified, and may be appropriately selected based onvarious purposes. Preferable examples of the coating method includeknown coating such as blade coating, wire bar coating, spray coating,air knife coating, bead coating, curtain coating, gravure coating, kisscoating, reverse roll coating, dip coating, and die coating.

A drying condition for the coating liquid for the thermoreversiblerecording medium is not particularly specified, and may be appropriatelyselected based on various purposes. Preferable examples of the dryingcondition include the temperature range of room temperature to 140° C.,and drying duration of 10 s to 10 min.

A thickness of the thermoreversible recording layer is not particularlyspecified, and may be appropriately selected based on various purposes.However, the thickness of the thermoreversible recording layer may bepreferably in a range of 1 to 20 μm, and more preferably 3 to 15 μm. Ifthe thermoreversible recording medium is too thin, coloring density islowered, thereby obtaining low image contrast. However, if thethermoreversible recording medium is too thick, the distribution of heatis increased in the layer. This causes part of the thermoreversiblerecording medium not to reach the color development temperature to leavethe part uncolored. Thus, desired coloring density may not be obtained.

—Photothermal Conversion Layer—

The photothermal conversion layer includes at least a photothermalconversion material capable of generating heat by efficiently absorbingthe laser beam. Further, barrier layers may be formed between thethermoreversible recording layer and the photothermal conversion layerto control adverse interaction between the thermoreversible recordinglayer and the photothermal conversion layer, and the barrier layers maybe preferably formed of a material having excellent thermalconductivity. A layer sandwiched between the thermoreversible recordinglayer and the photothermal conversion layer is not particularlyspecified, and may be appropriately selected based on various purposes.

Materials for the photothermal conversion layer may be either aninorganic material or organic material.

Examples of the inorganic material include carbon black, metal such asGe, Bi, In, Te, Se, and Cr, a semimetal or an alloy including thesemimetal, which are formed into a layer by a vacuum deposition methodor bonding particles of the material with resin.

Examples of the organic material include various dyes appropriatelyselected based on absorbing optical wavelengths. However, when asemiconductor laser (i.e., a laser diode, LD) is used as a light source,near-infrared dyes having an absorption peak within a wavelength rangeof 700 to 1,500 nm may be used. Specific examples of the near-infrareddyes include cyanine dyes, quinone dyes, quinoline derivatives of Indiannaphthol, phenylenediamine nickel complex, and phthalocyanine compounds.The photothermal conversion material having excellent heat resistancemay be preferably selected for repeatedly carrying out image processing,and the phthalocyanine compounds may be preferably selected as thephotothermal conversion material having excellent heat resistance.

The above near-infrared dyes may be used alone or may be used incombination of two or more.

The photothermal conversion material is usually combined with resin toform the photothermal conversion layer. The resin used for thephotothermal conversion layer is not particularly specified, and may beappropriately selected from known photothermal conversion layers insofaras the selected photothermal conversion layer can hold the inorganic ororganic materials. Preferable examples of the photothermal conversionlayer include thermoplastic resin and thermosetting resin, which aresimilar to resins used as the binder resin for the thermoreversiblerecording layer. Among these, the resin that is curable by theapplication of heat, UV rays, and electron beams is preferable in orderto improve durability for repeated use, and the resin that is thermallycrosslinked by using the isocyanate compounds as cross-linking agentsmay be particularly preferable. The binder resin includes a hydroxylvalue in a range of preferably 50 to 400 mgKOH/g.

A thickness of the photothermal conversion layer is not particularlyspecified, and may be appropriately selected based on various purposes.However, the thickness of the photothermal conversion layer may bepreferably in a range of 0.1 to 20 μm.

—First Oxygen Barrier Layer and Second Oxygen Barrier Layer—

The first oxygen barrier layer and the second oxygen barrier layer(hereinafter also called as an “oxygen barrier layer”) may preferably beprovided above or beneath the first or the second thermoreversiblerecording layer for preventing photodegradation of the leuco dyescontained in the first and second thermoreversible recording layers.That is, it is preferable that the first oxygen barrier layer beprovided between the supporting member and the first theroreversiblerecording layer, and the second oxygen barrier layer be provided on thesecond thermoreversible recording layer.

Materials of the first oxygen barrier layer and the second oxygenbarrier layer are not particularly specified, and may be appropriatelyselected based on various purposes; however, preferable examples of thematerials include resin or polymer film having high transparency invisible regions and low oxygen transmission. The materials of the oxygenbarrier layer may be selected based on application, oxygen transmission,transparency, coatability, and adhesiveness.

Specific examples of the oxygen barrier layers include alkylpolyacrylate ester resin, alkyl methacrylate ester resin,polymethacrylonitrile resin, polyalkyl vynil ester resin, polyalkylvynil ether resin, polyvinyl fluoride resin, polystyrene resin, vinylacetate copolymer resin, acetylcellulose resin, polyvinyl alcohol resin,polyvinylidene chloride resin, polyvinylidene chloride copolymer resin,acetonitrile copolymer resin, vinylidene chloride copolymer resin,poly(chlorotrifluoroethylene) resin, ethylene-vinylalcohol copolymerresin, polyacrylonitrile resin, polyacrylonitrile copolymer resin,polyethylene terephthalate resin, and nylon-6 and polyacetal resin, or asilica deposition film, an alumina deposition film, silica/aluminadeposition film obtained by depositing inorganic oxides on polymer filmssuch as polyethylene terephthalate or nylon. Among these, the inorganicoxide deposition films are preferable.

The oxygen transmission of the oxygen barrier layers is not particularlyspecified; however, 20 ml/m²/day/MPa or less may be preferable, 5ml/m²/day/MPa or less may be more preferable, and 1 ml/m²/day/MPa orless may be particularly preferable. If the oxygen transmission of theoxygen barrier layers exceeds 20 ml/m²/day/MPa, the opticaldeterioration of the leuco dyes in the first and second thermoreversiblerecording layers may not be controlled.

The oxygen transmission of the oxygen barrier layers may be measuredbased on a measurement method in accordance with JIS K7126.

Note that the oxygen barrier layers may be arranged at a lower side ofthe thermoreversible recording layer or a rear side of the supportingmember to sandwich the thermoreversible recording layer. With thisconfiguration, the oxygen transmission into the thermoreversiblerecording layer may be prevented, thereby reducing the opticaldeterioration of the leuco dyes.

Methods of forming the first oxygen barrier layer and the second oxygenbarrier layer are not particularly specified, and may be appropriatelyselected based on various purposes; however, preferable examples of themethods include a melt-extrusion method, a coating method, and alaminating method.

The thickness of the first or second oxygen barrier layer varies withthe oxygen transmission to the resin or polymer film; however, thethickness of the oxygen barrier layer may be preferably 0.1 to 100 μm.If the thickness of the oxygen barrier layer is less than 0.1 μm, theoxygen barrier layer may not sufficiently prevent the oxygentransmission, whereas if the thickness of the oxygen barrier layer isgreater than 100 μm, the transparency of the oxygen barrier layer may bereduced.

The adhesive layer may be provided between the oxygen barrier layer andthe layer below the oxygen barrier layer. A method of forming theadhesive layer is not particularly specified, and may be one of thecoating method and the laminating method. A thickness of the adhesivelayer is not particularly specified, and may be preferably in a range of0.1 to 5 μm. The adhesive layer may be cured by a crosslinking agent.The same crosslinking agent used for the thermoreversible recordinglayer may be appropriately used as the crosslinking agent for curing theadhesive layer.

—Protection Layer—

It is preferable that a protection layer be provided on thethermoreversible recording layer for protecting the thermoreversiblerecording layer. The protection layer is provided in any fashion basedon various purposes. For example, one or more protection layers may beprovided on the thermoreversible recording layer. The protection layermay be preferably provided on an outermost surface of thethermoreversible recording layer.

The protection layer may include binder resin, and optionally includefillers, lubricants, color pigments, and other components.

The binder resin of the protection layer is not particularly specified,and may be appropriately selected based on various purposes. However,preferable examples of the binder resin used for the protection layermay include thermosetting resin, ultraviolet (UV) curable resin, curableresin, and electron beam curable resin.

If the UV curable resin is used for forming the protection layer, asignificantly hard film may be obtained after curing. Accordingly, thedeformation of the obtained thermoreversible recording medium due tophysical surface contact or heat by the laser beam may be suppressed,and the thermoreversible recording medium having excellent repeateddurability may be obtained.

If the curable resin is used for forming the protection layer, thethermoreversible recording medium may still obtain a hard surface andrepeated durability, though the hardness of the surface formed of thecurable resin is less hard than that formed of the UV curable resin.

The material of the UV curable resin is not particularly specified, andmay be appropriately selected from the known UV curable resins based onthe purposes. Examples of the UV curable resins include urethaneacrylate oligomer, epoxy acylate oligomer, polyester acrylate oligomer,polyether acrylate oligomer, vinyl oligomer, and saturated polyesteracrylate oligomer; monofunctional or polyfunctional acrylate monomer,methacrylate monomer, vinyl ester monomer, ethylene derivative monomer,and allyl compound monomer. Among these, polyfunctional(tetrafunctional) monomer or oligomer is particularly preferable. Thehardness, degree of contraction, plasticity and film strengthens of theresin film may be appropriately controlled by combining two or more ofthe above monomers and oligomers.

Further, a photopolymerization initiator or photopolymerizationaccelerator may need to be added for curing the monomers or oligomers byapplying UV rays.

The amount of the photopolymerization initiator or photopolymerizationaccelerator is not particularly specified; however, it may be preferablyin a range of 0.1 to 20 mass %, and more preferably 1 to 10 mass % basedon the overall amount of the resin component of the protection layer.

Any known UV application device may be used for applying the UV rays tothe UV curable resin for curing; however, the UV application device maypreferably include a light source, lamp fittings, a power source, acooling device, and a transferring device.

Examples of the light source include a mercury lamp, a metal halidelamp, a potassium lamp, a mercury xenon lamp, and a flash lamp. Thewavelength of the light source may be appropriately selected based onthe UV absorption wavelength of the photopolymerization initiator orphotopolymerization accelerator added to the thermoreversible recordingmedium composition.

A UV ray application condition is not particularly specified, and may beappropriately selected based on various purposes. The UV ray applicationcondition may include a lamp output power or transferring speeddetermined based on the irradiation energy required for crosslinking theresin.

Moreover, a releasing agent such as a silicone polymer having apolymerization group, a graphite silicone polymer, wax and zincstearate, and a lubricant such as a silicone oil may be added forimproving the transferability. The amount of the above materials forimproving the transferability is not particularly specified; however, itmay be preferably in a range of 0.01 to 50 mass %, and more preferablyin a range of 0.1 to 40 mass % based on the overall amount of the resincomponent of the protection layer. The above materials for improving thetransferability may be used alone or may be used in combination of twoor more. Further, conductive filler may be preferably added as acountermeasure against static electricity, and acicularelectro-conductive filler may be more preferably added.

A particle size of the inorganic pigment is not particularly limited,and may be preferably in a range of 0.01 to 10.0 μm, and more preferablyin a range of 0.05 to 8.0 μm. The amount of the inorganic pigment to beadded is not particularly specified; however, it may be preferably in arange of 0.001 to 2 mass %, and more preferably in a range of 0.005 to 1mass % based on 1 mass % of the heat resistant resin.

Note that the protection layer may include known surfactants, levelingagents, and antistatic agents as additives.

Further, as the thermosetting resin, the resin similar to the binderresin used for the thermoreversible recording layer may be suitablyused.

The thermosetting resin may be preferably crosslinked. Thus, thethermosetting resin may preferably include a group that reacts with acuring agent, such as an amino group and a carboxyl group, and morepreferably include a polymer including a hydroxyl group. The polymer forimproving the strength of the polymer-containing layer having theUV-absorption structure may also be added. The polymer having a hydroxylgroup value of 10 mgKOH/g or more may be preferably added, the polymerhaving a hydroxyl group valence of a hydroxyl group value of 30 mgKOH/gor more may be more preferably added, ° and the polymer having ahydroxyl value of 40 mgKOH/g or more may be most preferably added forobtaining sufficient film strength. If the thermosetting resin has thestrong film, the deterioration obtained due to the repeated recordingand erasure may be suppressed.

The curing agent is not particularly specified; however, the curingagent similar to that used for the thermoreversible recording layer maybe suitably used.

The solvents, coating liquid dispersing devices, coating methods, anddrying methods used for coating the protection layer are notparticularly specified; however, any known solvents, coating liquiddispersing devices, coating methods for coating the protection layer,and drying methods for drying the coated film used for thethermoreversible recording medium may be used. If the UV curable resinis used, the curable process needs to include coating, drying, andapplying the UV rays to the UV curable resin; however, the UV rayapplication device, the light source and the UV ray applicationcondition may be the same as the ones described above.

The thickness of the protection layer is not particularly specified, andmay be preferably in a range of 0.1 to 20 μm, more preferably in a rangeof 0.5 to 10 μm, and most preferably in a range of 1.5 to 6 μm. If thethickness of the protection layer is less than 0.1 μm, the protectionlayer may not sufficiently function to protect the thermoreversiblerecording medium. As a result, the thermoreversible recording medium mayquickly deteriorate due to repeated application of heat, and thus maynot be repeatedly used. On the other hand, if the thickness of theprotection layer exceeds 20 μm, sufficient heat may not be transmittedto the thermosensitive layer (i.e., thermoreversible recording layer)located below the protection layer. As a result, the image may not besufficiently recorded on or erased from the thermoreversible recordingmedium.

—UV Absorber Layer—

The thermoreversible recording medium may preferably include a UVabsorber layer at a side opposite to the side of the secondthermoreversible recording layer where the supporting member is providedin order to prevent remaining coloring of the leuco dyes in thethermoreversible recording layer due to the UV rays or failure todecolor the leuco dyes in the thermoreversible recording layer due tothe optical deterioration. Accordingly, the optical resistance of thethermoreversible recording medium with this configuration may beimproved. It is preferable that a thickness of the UV absorber layer beappropriately selected such that the UV absorber layer absorbs the UVrays of 390 nm or less.

The UV absorber layer at least includes a binder resin and a UV absorberagent, and may optionally include fillers, lubricants, coloringpigments, and other components.

The binder resin is not particularly specified, and may be appropriatelyselected based on various purposes. However, the above described binderresin used for the thermoreversible recording layer, thermoplasticresin, and thermosetting resin may be preferable. Examples of thecomponents for the resin include polyethylene, polypropylene,polystyrene, polyvinyl alcohol, poly vinyl butyral, polyurethane,saturated polyester, unsaturated polyester, epoxy resin, phenol resin,polycarbonate, and polyamide.

The UV absorber agent may be formed of organic or inorganic compounds.

It is preferable to use a polymer having a UV absorber structure(hereinafter also called a “UV absorber polymer”).

The UV absorber agent indicates a polymer having the UV absorberstructure (i.e., a UV absorber group) in molecules. Examples of the UVabsorber structure include a salicate structure, a cyanoacrylatestructure, a benzotriazole structure, and a benzophenone structure.Among these, the benzotriazole structure, and the benzophenone structureare particularly preferable because they absorb the UV lays having thewavelength range of 340 to 400 nm that cause the optical deteriorationof the leuco dyes.

It is preferable that the UV absorber polymer be crosslinked.Accordingly, the UV absorber polymer preferably includes a group capableof reacting with the curing agent such as an amino group or a carboxylgroup, and more preferably includes a hydroxyl group. In order toimprove the strength of the polymer containing layer having the UVabsorber structure, the UV absorber polymer preferably includes thehydroxyl value of 10 mgKOH/g or more, more preferably includes thehydroxyl value of 30 mgKOH/g or more, and most preferably includes thehydroxyl value of 40 mgKOH/g or more. If the UV absorber layer hassufficient film strength, the deterioration of the thermoreversiblerecording medium due to the repeated recording and erasure may besuppressed.

A thickness of the UV absorber layer is not particularly specified, andmay be preferably in a range of 0.1 to 30 μm, and more preferably in arange of 0.5 to 20 μm. Any known solvents, coating liquid dispersingdevices, coating methods, and drying-curing methods used for the formingthe thermoreversible recording layer may be used for forming the UVabsorber layer.

—Intermediate Layer—

The thermoreversible recording medium is not particularly specified;however, it is preferable that the thermoreversible recording mediuminclude an intermediate layer for improving the adhesiveness between thethermoreversible recording layer and the protection layer, preventingthe deterioration of thermoreversible recording layer due to theapplication of the protection layer, and preventing the transition ofthe additives in the protection layer to the thermoreversible recordinglayer.

The intermediate layer is not particularly specified; however, theintermediate layer preferably includes at least a binder resin, and mayoptionally include fillers, lubricants, coloring pigments, and othercomponents.

The binder resin is not particularly specified, and may be appropriatelyselected based on various purposes. However, the above described binderresin used for the thermoreversible recording layer, thermoplasticresin, and thermosetting resin may be preferable. Examples of thecomponents for the resin include polyethylene, polypropylene,polystyrene, polyvinyl alcohol, poly vinyl butyral, polyurethane,saturated polyester, unsaturated polyester, epoxy resin, phenol resin,polycarbonate, and polyamide.

Further, it is preferable that the intermediate layer include the UVabsorber agent. The UV absorber agent may be formed of organic orinorganic compounds.

The intermediate layer may include a UV absorber polymer and may becured using the crosslinking agent. The crosslinking agent used for theprotection layer may be suitably used for the intermediate layer.

A thickness of the intermediate layer may be preferably in a range of0.1 to 20 μm, and more preferably in a range of 0.5 to 5 μm. Any knownsolvents, coating liquid dispersing devices, coating methods, anddrying-curing methods used for the forming the thermoreversiblerecording layer may be used for forming the intermediate layer.

—Under Layer—

The thermoreversible recording medium is not particularly specified;however, it is preferable that the thermoreversible recording mediuminclude an under layer for improving the sensitiveness of thethermoreversible recording medium by efficiently utilizing the appliedheat, improving the adhesiveness between the thermoreversible recordinglayer and the supporting member, and preventing the transition of thematerials in the thermoreversible recording layer to the supportingmember.

The under layer may at least include hollow particles, may preferablyinclude the binder resin, and may optionally include other components.

Examples of the hollow particles include hollow particles each having asingle pore and porous particles each having multiple pores. The abovetypes of the hollow particles may be used alone or may be used incombination of two or more.

Materials of the hollow particles are not particularly specified;however, the thermosetting resin may be preferably used. The abovehollow particles may be suitably manufactured or commercially availablehollow particles may be used. Examples of the commercially availablehollow particles include Matsumoto Microsphere R-series (manufactured byMatsumoto Yushi-Seiyaku Co., Ltd), Rohpake HP-1055 and Rohpake HP-433J(manufactured by Zeon Corporation), and SX866 (manufactured by JSR).

The amount of the hollow particles to be added for the under layer isnot particularly specified, and may be appropriately selected based onvarious purposes. However, amount of the hollow particles to be addedmay be preferably in a range of 10 to 80 mass %.

The same binder resin used for the thermoreversible recording layer orthe UV absorber polymer having the UV absorber structure may be used forthe under layer.

The under layer may at least include one of inorganic fillers selectedfrom calcium carbonate, magnesium carbonate, titanium oxide, siliconoxide, aluminum hydroxide, kaoline, talc, or one of various organicfillers.

Note that the under layer may additionally include lubricants,surfacants, and dispersing agents.

A thickness of the under layer is not particularly specified, and may beappropriately selected based on various purposes. However, the thicknessof the under layer may be preferably in a range of 0.1 to 50 μm, morepreferably in a range of 2 to 30 μm, and most preferably in a range of12 to 24 μm.

—Backing Layer—

The thermoreversible recording medium is not particularly specified;however, the thermoreversible recording medium may include a backinglayer at a side opposite to the side of the supporting member where thethermoreversible recording layer is provided, in order to preventcurling and static charge, and improve the transferability.

The backing layer is not particularly specified; however, the backinglayer preferably includes at least a binder resin, and may optionallyinclude fillers, electro-conductive fillers, lubricants, coloringpigments, and other components.

The binder resin is not particularly specified, and may be appropriatelyselected based on various purposes. Preferred examples of the binderresin include thermosetting resin, ultraviolet (UV) curable resin, andelectron beam curable resin. Among these, the ultraviolet (UV) curableresin and thermosetting resin may be particularly preferable.

The UV curable resin, the thermosetting resin, the filler, theconductive filler, and the lubricant used for the thermoreversiblerecording layer or the protection layer may be suitably used for thebacking layer.

—Adhesive Layer and Cohesion Layer—

The thermoreversible recording medium is not particularly specified, andmay be used as a thermoreversible recording label by providing anadhesive layer or a cohesion layer at a side opposite to athermoreversible recording layer forming surface of the supportingmember of the thermoreversible medium. Materials for the adhesive layeror cohesion layer may be any materials generally used for the adhesivelayer or cohesion layer.

Specific materials for the adhesive layer or cohesion layer are notparticularly specified, and may be appropriately selected based onvarious purposes. However, preferable examples of the specific materialsfor the adhesive layer or cohesion layer may include urea resin,melamine resin, phenol resin, epoxy resin, vinyl acetate resin, vinylacetate-acrylic copolymers, ethylene-vinyl acetate copolymers, acrylicresin, polyvinyl ether resin, chloridization vinyl-vinyl acetatecopolymers, polystyrene resin, polyester resin, polyurethane resin,polyamide resin, chlorinated polyolefin resin, polyvinyl butyral resin,acrylic ester copolymers, methacrylate ester copolymer, natural rubber,cyanoacrylate resin, and silicone resin.

The materials for the adhesive layer or cohesion layer may be hot-melttypes. The hot-melt materials for the adhesive layer or cohesion layermay utilize releasing paper or may not utilize the releasing paper.Accordingly, the thermoreversible recording label to which the adhesivelayer or cohesion layer is provided may be attached on an entire surfaceor part of the surface of the thick substrate such as a vinyl chloridecard having magnetic stripes to which the recording layer is difficultto apply. Thus, since part of the information recorded in the magnet isdisplayed on the medium, the convenience of the medium may be improved.The thermoreversible recording label having the adhesive layer orcohesion layer may be applied to a thick card such as an IC card or anoptical card.

The thermoreversible recording medium is not particularly specified, andmay include a coloring layer between the supporting member and therecording layer for improving the visibility.

The coloring layer is not particularly specified; however, the coloringlayer may be formed by applying a solution containing a coloring agentand the binder resin or a dispersing liquid to a target surface anddrying, or by attaching a colored sheet on the target surface.

The thermoreversible recording medium may include a color printinglayer. Examples of a coloring agent for forming the color printing layermay be various dyes or pigments contained in the conventional ink usedfor full-color printing, and examples of the binder resin may includethermoplastic resin, thermosetting resin, UV curable resin, and electronbeam curable resin. Since a thickness of the color printing layer isappropriately changed based on the printing color density, the thicknessof the color printing layer may be selected based on desired printingdensity.

The thermoreversible recording medium may include a non-reversiblerecording layer. In this case, the developing color of thethermoreversible recording layer and non-reversible recording layer mayeither be the same or different. The thermoreversible recording mediummay include the coloring layer provided on part of or an entire surfaceor opposite surface of the recording layer. The coloring layer mayinclude optional patterns provided by offset printing, and gravureprinting, or by an inkjet printer, a thermal transfer printer, or asublimatic printer. Further, a double-sided overprint (OP) varnish layerhaving curable resin as a main component may be provided on the part orentire surface of the coloring layer. The optional patterns may includecharacters, patterns, design, photographs, and infrared ray detectableinformation. Alternatively, one of the above layers may be colored withdyes or pigments.

The thermoreversible recording medium may include a hologram forsecurity. Further, a relief forming a portrait, a company emblem, orsymbols may be formed in the thermoreversible recording medium forproviding a particular design.

The thermoreversible recording medium may be formed in any desired shapeor form, such as a card shape, tag shape, label shape, sheet shape, androll shape. The card shaped thermoreversible recording medium may beapplied as a prepaid card, a point card, or a credit card. The tagshaped thermoreversible recording medium that is smaller than the cardshaped thermoreversible recording medium may be applied as a price tag.The tag shaped thermoreversible recording medium that is larger than thecard shaped thermoreversible recording medium may be applied as aprocess control form, a delivery instruction form, or a ticket. Sincethe label shaped thermoreversible recording medium that is capable ofattaching is formed into various sizes, they are applied to repeatedlyused wagons, containers, and boxes for managing the process control ormanaging articles. The sheet shaped thermoreversible recording mediumthat is larger than the card shaped thermoreversible recording mediumhas a large area for recording images and may be used as ageneral-purpose document, and an instruction form of the process controlform.

<Combination Example of Thermoreversible Recording Member with RF-ID>

The thermoreversible recording member used in the embodiments mayprovide excellent convenience by integrating the reversibly displayingrecording layer and information recording portion in the same card ortag and displaying part of the recorded information recorded in theinformation recording portion, such that a user can recognize theinformation by simply looking at the card or tag without any (reading)device. Further, when the content of the information recording portionis changed, the thermoreversible recording medium may be repeatedly usedby changing the display of the thermoreversible recording medium.

The information recording portion is not particularly specified, and maybe appropriately selected based on various purposes. However, preferableexamples of the information recording portion include a magneticrecording layer, magnetic stripes, an IC memory, an optical memory, andan RF-ID tag. If the information recording portion is used for processcontrol or article management, an RF-ID tag is preferably used. Notethat the RF-ID tag includes an IC chip, and an antenna connected to theIC chip.

The thermoreversible recording member includes the recording layercapable of reversibly displaying information and the informationrecording portion, and the RF-ID tag is preferably used as theinformation recording portion.

FIG. 18 is a schematic diagram illustrating an example of an RF-ID tag485. The RF-ID tag 485 includes an IC chip 481, and an antenna 482connected to the IC chip 481. The IC chip 481 includes four sections ofa recording section, a power source adjusting section, a transmissionsection, and a receiving section, which share communication functions.The communication is carried out by transmission of radio waves betweenthe RF-ID tag and a reader-writer antenna. Specifically, there are twotypes of communication system, a first one is an electromagneticinduction system where electromotive force is generated by resonanceeffect when the RF-ID antenna receives radio waves from thereader-writer antenna, and a second one is an electric radiation systemwhere electromotive force is generated by a radiation field. In bothsystems, the IC chip of the RF-ID tag is activated by the externalelectromagnetic field, information in the IC chip is converted intosignals, and the converted signals are transmitted from the RF-ID tag.The transmitted information is received by the reader-writer antenna,the received information is recognized by a data processing device, andthe data are processed by software of the data processing device.

The RF-ID tag is formed in a label shape or card shape, such that theRF-ID tag may be attached to the thermoreversible recording medium. TheRF-ID tag may be attached to a surface of the recording layer or thebacking layer; however, the RF-ID tag may preferably be attached to thesurface of the backing layer. Any known binders or adhesives may be usedfor adhering the RF-ID tag with the thermoreversible recording medium.

Further, the thermoreversible recording medium and the RF-ID tag may beintegrated into a card or a tag by a laminating process, or the like.

<Image Recording and Erasing Mechanism>

An image recording and erasing mechanism is achieved by reversing thecolors of the thermoreversible recording medium with heat. Thethermoreversible recording medium includes the leuco dyes and thereversible developer (hereinafter simply called a “developer”), wherethe color of the thermoreversible recording medium is reversibly changedbetween a developed colored state and a transparent state by theapplication of heat.

FIG. 19A illustrates an example of a temperature-color density changecurve in the thermoreversible recording medium having thethermoreversible recording layer(s) formed by mixing the leuco dyes andthe developers in the resin. FIG. 19B illustrates a coloring/decoloringmechanism in the thermoreversible recording medium where the transparentstate and developed color state are reversibly changed with the appliedheat.

As illustrated in FIG. 19A, when the recording layer in a decoloredstate A is heated to a melting temperature T1, the leuco dye and thedeveloper in the recording layer are melted and mixed so that therecording layer is colored in a melted colored state B. When therecording layer in the melted colored state B is rapidly cooled, atemperature of the recording layer is decreased to room temperaturewhile the recording layer maintains its colored state, therebystabilizing the colored state of the recording layer. Accordingly, therecording layer is in a solid colored state C. Whether the recordinglayer is capable of obtaining such a solid colored state depends on aspeed of heating or cooling the recording layer in the melted coloredstate B. If the recording layer is slowly cooled, the recording layer isdecolored to be in the initial decolored state A. If, on the other hand,the recording layer is rapidly cooled, the recording layer acquires arelatively dense color compared to that in the solid colored state A.Meanwhile, when the recording layer in the solid colored state C isheated again, the recording layer is decolored at a temperature T2 lowerthan a coloring temperature (from D to E), and if the recording layerhaving been in the solid colored state C is then cooled, the recordinglayer returns to the initial decolored state A.

In the recording layer in the solid colored state C changed from themelted state by rapid cooling, the colored leuco dye molecules and thedeveloper molecules are mixed while they remain in a contact reactivestate and the molecules in the contact reactive state often form solids.In this status, the melted mixture (colored mixture) of the leuco dyeand developer is crystallized while retaining its colored state, and dueto this crystallized structure, the color of the mixture may bestabilized. In contrast, a phase of the leuco dye and that of thedeveloper are separated in the decolored state. In the phase-separationstatus, the molecules of one of the leuco dye compound and the developercompound are cohered or crystallized, so that the leuco dye and thedeveloper are separately stabilized due to its cohesion orcrystallization. In many cases, more complete decoloration of therecording layer may be obtained due to the phase separation of the leucodye and the developer and crystallization of the developer.

Note that the decolored state A obtained by slow cooling from the meltedstate B of the recording layer or the decolored state A obtained byheating from the solid colored state C of the recording layerillustrated in FIG. 19A may result from changes in the cohered structureat temperature T2, thereby causing the phase separation andcrystallization of the developer.

Further, in FIG. 19A, erasing failure, where the recording layer heatingat an erasing temperature is unable to decolor, may occur if therecording layer is repeatedly heated to a temperature T3 equal to orhigher than the melting temperature T1. The erasing failure may resultfrom thermal decomposition of the developer, because the thermallydecomposed developer is resistant to cohesion or crystallization andthus may not be easily separate from the leuco dye. Deterioration of thethermoreversible recording medium due to repeated heating and coolingmay be controlled by decreasing the difference between the meltingtemperature T1 and the temperature T3 when heating the thermoreversiblerecording medium.

(Image Processing Apparatus)

An image processing apparatus according to the embodiment is used forcarrying out the marking control method, and is configured to include atleast a laser application unit to apply a laser beam, a laser beamscanning unit to scan the laser beam on a laser receiving surface, andoptionally includes other members.

The wavelength of the laser beam to be applied to the thermoreversiblerecording medium may be selected such that the thermoreversiblerecording medium efficiently absorbs the applied laser beam. Forexample, the thermoreversible recording medium may at least include atleast a photothermal conversion material capable of generating heat byefficiently absorbing the applied laser beam. The wavelength of thelaser beam to be applied to the thermoreversible recording medium mayneed to be selected such that the photothermal conversion material moreefficiently absorbs the applied laser beam than other materials.

—Laser Emitting Unit—

A wavelength of the laser beam emitted by a laser emitting unit may bepreferably 700 nm or more, more preferably 720 nm or more, andparticularly preferably 750 nm or more. An upper limit of the wavelengthof the laser beam emitted by a laser emitting unit is not particularlylimited, and may be appropriately selected based on various purposes.However, the upper limit of the wavelength of the laser beam may bepreferably 1,500 nm or less, more preferably 1,300 nm or less, andparticularly preferably 1,200 nm or less.

If the wavelength of the laser beam is shorter than 700 nm, the contrastof the image in a visible light region may be lowered while recordingthe image, or other regions of the thermoreversible recording medium maybe colored. In an ultraviolet light region having a wavelength furthershorter than the 700 nm of the visible light region, thethermoreversible recording medium may be damaged. Moreover, thephotothermal conversion material added to the thermoreversible recordingmedium may require a high decomposition temperature for obtainingdurability for repeated image processing. However, if the photothermalconversion material needs to contain an organic dye, it may be difficultto obtain the photothermal conversion material having a long absorptionwavelength and having high decomposition temperature. Thus, thewavelength of the laser beam may be preferably 1,500 nm or less.

The laser emitting unit is not particularly specified, and may beappropriately selected based on various purposes; however, preferableexamples of the laser emitting unit include a YAG (yttrium aluminiumgarnet) laser, a fiber laser, and a semiconductor laser (i.e., a laserdiode, LD). Among these, the semiconductor laser is particularlypreferable due to having a wide selection of the wavelength range,thereby increasing the optional photothermal conversion material range.Further, since the semiconductor laser has a small laser light source,the laser device having the semiconductor laser may be reduced in sizeand may be fabricated at low cost.

The image processing apparatus has a basic configuration similar to thatof the laser marker including the laser emitting unit, and at leastadditionally includes an oscillator unit, a power control unit, and aprogram unit.

FIG. 20 illustrates an example of the image processing apparatus used inthe above embodiments, where the laser emitting unit is focused on.

The oscillator unit is configured to include a laser oscillator 401, abeam expander 402, and a scanning unit 405 (laser beam scanning unit).

The laser oscillator 401 is provided for increasing optical intensityand directivity of the laser beam. Accordingly, in the laser oscillator401, a mirror is arranged at both sides of a laser medium to pump thelaser medium (energy supply) to increase excited state atoms such thatan inverted distribution is formed to induce laser emission. The laserbeams in an optical axis direction are amplified to increase thedirectivities of the laser beams, so that the laser beam is emitted froman output mirror.

The scanning unit 405 is configured to include galvanometers 404 andgalvanometer mirrors 404A attached to the corresponding galvanometers404. The laser beam output from the laser oscillator 401 is thenrotationally scanned at a high speed by the X-axis directional mirror404A and the Y-axis directional mirror 404A attached to the respectivegalvanometers 404 to apply the laser beam on a thermoreversiblerecording medium 407, thereby recording or erasing the image on thethermoreversible recording medium 407.

The power control unit is configured to include a drive power that is alight source for exciting a laser medium, drive power for thegalvanometers, cooling power source for a Peltier device, and a controlunit for controlling an entire image processing apparatus.

The program unit is configured to control the laser beam intensity, andinput of a condition such as laser scanning speed, and also create oredit characters or images to be recorded or erased via a touch panel ora keyboard.

Note that the laser application unit that is an image recording/erasinghead is provided in the image processing apparatus. Further, the imageprocessing apparatus includes a transfer unit for transferring thethermoreversible recording medium, a control unit for the transfer unit,and a monitor unit (i.e., touch panel).

EXAMPLES

Although examples of the embodiments are described below, theembodiments are not limited to these examples.

Manufacturing Example 1 Manufacture of Thermoreversible Recording Medium

A thermoreversible recording medium capable of reversibly changing itscolor with applied heat was manufactured as follows.

—Supporting Member—

A white polyester film having a thickness of 125 μm (Tetoron FilmU2L98W; manufactured by Teijin DuPont Films Japan Limited) was used as asupporting member.

—Forming of First Thermoreversible Recording Medium—

Five parts by mass of a reversible developer represented by thestructural formula (1), 0.5 parts by mass of a first decoloringaccelerator represented by the structural formula (2), 0.5 parts by massof a second decoloring accelerator represented by the structural formula(3), 10 parts by mass of a solution containing 50 mass % acrylic polyol(hydroxyl value=200 mgKOH/g), and 80 parts by mass of methyl ethylketone were ground and dispersed by a ball mill until they had a meanparticle size of approximately 1 μm.

Next, one part by mass of 2-anilino-3-methyl-6-dibutylaminofluoran asthe leuco dye, and 5 parts by mass of isocyanate (Coronate HL;manufactured by Nippon Polyurethane Industries, Co., Ltd.) were added tothe obtained dispersion having the dispersed ground reversible developerparticles, and the mixture was sufficiently stirred, thereby preparing athermoreversible recording layer coating liquid.

The obtained thermoreversible recording layer coating liquid was coatedon the supporting member with a wire bar, the coated supporting memberwas dried at 100° C. for 2 minutes, and the dried supporting member wasthen cured at 60° C. for 24 hours, thereby obtaining a firstthermoreversible recording layer having a thickness of 9.6 μm.

—Forming of Photothermal Conversion Layer—

Four parts by mass of a solution containing 1 mass % phthalocyaninephotothermal conversion material (IR-14, absorption wavelength peak: 824nm; manufactured by Nippon Shokubai Co., Ltd.), 10 parts by mass of asolution containing 50 mass % aclyic polyol (a hydroxyl value=200mgKOH/g), 20 parts by mass of methyl ethyl ketone, and 5 parts by massof isocyanate (Coronate HL; manufactured by Nippon PolyurethaneIndustries, Co., Ltd.) as a crosslinker were mixed and sufficientlystirred, thereby preparing a photothermal conversion layer coatingliquid. The obtained photothermal conversion layer coating liquid wascoated on the first thermoreversible recording layer with a wire bar,the coated first thermoreversible recording layer was dried at 90° C.for 1 minute, and the dried first thermoreversible recording layer wasthen cured at 60° C. for 24 hours, thereby obtaining a photothermalconversion layer having a thickness of 4 μm.

—Forming of Second Thermoreversible Recording Medium—

The obtained thermoreversible recording layer coating liquid (samecoating liquid used for the first thermoreversible recording layer) wascoated on the photothermal conversion layer with a wire bar, the coatedphotothermal conversion layer was dried at 100° C. for 2 minutes, andthe dried photothermal conversion layer was then cured at 60° C. for 24hours, thereby obtaining a second thermoreversible recording layerhaving a thickness of 2.4 vim.

—Forming of Photothermal Conversion Layer—

Ten parts by mass of a solution containing 40 mass % UV absorber polymer(UV-G300; manufactured by Nippon Shokubai Co., Ltd.), 1.5 parts by massof isocyanate (Coronate HL; manufactured by Nippon PolyurethaneIndustries, Co., Ltd.), and 12 parts by mass of methyl ethyl ketone weremixed and the mixture was sufficiently stirred, thereby preparing a UVabsorber layer coating liquid.

Next, the obtained UV absorber layer coating liquid was coated on thesecond thermoreversible recording layer of the supporting member with awire bar, where the second thermoreversible recording layer is formed onthe photothermal conversion layer, and the photothermal conversion layeris formed on the supporting member; the coated layer was dried at 90° C.for 1 minute, and the coated layer was then cured at 60° C. for 24hours, thereby obtaining a UV absorber layer having a thickness of 2 μm.

Note that as will be described later, a second oxygen barrier layer wasprovided on the UV absorber layer and a first oxygen barrier layer wasprovided between the first thermoreversible recording layer and thesupporting member.

—Forming of First Oxygen Barrier Layer and Second Oxygen Barrier Layer—

Five parts by mass of an urethane adhesive (TM-567; manufactured byToyo-Morton, Ltd.), 0.5 parts by mass of isocyanate (CAT-RT-37;manufactured by Toyo-Morton, Ltd.), and 5 parts by mass of ethyl acetatewere mixed and the mixture was sufficiently stirred, thereby preparingan oxygen barrier layer coating liquid.

Next, the oxygen barrier layer coating liquid was coated on a silicadeposited PET (polyethylene terephthalate) film (Techbarrier HX, OxygenTransmission: 0.5 ml/m²/day/MPa; manufactured by Mitsubishi Plastics,Inc.) with a wire bar, the coated film was dried at 80° C. for 1 minute,and the coated film was then cured at 50° C. for 24 hours; the curedcoated film was adhered to the UV absorber layer and to the supportingmember, respectively, thereby forming a first oxygen barrier layer and asecond oxygen barrier layer each having a thickness of 12 μm.

—Forming of Backing Layer—

7.5 parts by mass of pentaerythritol hexaacrylate (KAYARAD DPHA;manufactured by Nippon Kayaku Co., Ltd.), 2.5 parts by mass of urethaneacrylate oligomer (Art resin UN-3320HA; manufactured by Negami ChemicalIndustrial Co., Ltd.), 2.5 parts by mass of acicular electro-conductivetitanium oxide (FT-3000: long axis=5.15 μm, short axis=0.27 μm;manufactured by Ishihara Sangyo Kaisha, Ltd.), 0.5 parts by mass of aphotopolymerization initiator (Irgacure 184; manufactured by NihonCiba-Geigy K.K.), and 13 parts by mass of isopropyl alcohol were mixedand sufficiently stirred by a ball mill, thereby preparing a backinglayer coating liquid.

Next, the obtained backing layer coating liquid was coated on a side ofthe supporting member where the above layers were not formed with a wirebar, the coated supporting member was heated and dried at 90° C. for 1minute, and the coated supporting member was then crosslinked by a UVlamp having lamp power of 80 W/cm, thereby obtaining a backing layerhaving a thickness of 4 μm. Thus, the thermoreversible recording mediumwas manufactured by following a method of Manufacturing Example 1.

Manufacturing Example 2 Manufacture of Thermoreversible Recording Medium

A thermoreversible recording medium was manufactured by following amethod of Manufacturing Example 2 in the same manner as the method ofmanufacturing example 1, except that in the preparation of thephotothermal conversion material, 2 parts by mass of a solutioncontaining 0.5 mass % cyanin photothermal conversion material (YKR-2900,absorption wavelength peak: 830 nm; manufactured by Yamamoto ChemicalsInc.) was added instead of adding 4 parts by mass of the solutioncontaining 1 mass % phthalocyanine photothermal conversion material tothe prepare photothermal conversion layer coating liquid. Note that thecyanin photothermal conversion material (YKR-2900; manufactured byYamamoto. Chemicals Inc.) was added in an amount such that the cyaninphotothermal conversion material obtains the thermosensitivity similarto that of the phthalocyanine photothermal conversion material obtainedin Manufacturing Example 1.

Solidly Filled Image Printing (Image Recording) Example 1

An image recording process was conducted by a LD marker device. In theimage recording process (conducted by the LD marker device), laser beamswere applied to the thermoreversible recording medium obtained inManufacturing Example 1 by ES-6200-A (central wavelength: 808 nm) of aQPC fiber-coupled laser diode (semiconductor laser), the applied laserbeams were collimated by two collimator lenses (focal length: 26 mm),the collimated laser beams were scanned by a galvanoscanner 6230H(manufactured by Cambridge Technology), and the scanned laser beams werethen converged on the thermoreversible recording medium with a fθ lens(focal length: 141 mm). In Example 1, a working distance was adjusted at141 mm (a beam diameter: 0.65 mm), a linear speed was adjusted at 2,500mm/s, and the image recording was conducted based on a laser beamscanning method illustrated in FIG. 21A (i.e., 4 A-directional markinglines, 6 B-directional marking lines, and 3 C-directional markinglines). In Example 1, a solidly filled image was recorded such that apitch width was set at 0.20 mm between an A-directional marking line anda C-directional marking line located adjacent to the A-directionalmarking line, a slanted amount of the C-directional marking line to theA-directional marking line was set at 0.09 mm, and a length of theA-directional marking line was set at 10 mm. The irradiation power ofthe laser beam was selected so that image density was saturated.

Example 2

In Example 2, the image recording was conducted based on a laser beamscanning method illustrated in FIG. 21B (i.e., 4 A-directional markinglines, 3 C-directional marking lines, and no B-directional markinglines) instead of the laser beam scanning method illustrated in FIG.21A. In Example 2, a solidly filled image was recorded in the samemanner as the Example 1, where a pitch width was set at 0.20 mm betweenan A-directional marking line and a C-directional marking line adjacentto the A-directional marking line, a slanted amount of the C-directionalmarking line to the A-directional marking line was set at 0.09 mm, and alength of the A-directional marking line was set at 10 mm.

Example 3

In Example 3, the image recording was conducted in the same manner asthe Example 2, except that a slanted amount of the C-directional markingline to the A-directional marking line was changed from 0.09 mm (Example2) to 0.045 mm (Example 3).

Example 4

In Example 4, the image recording was conducted in the same manner asthe Example 2, except that a slanted amount of the C-directional markingline to the A-directional marking line was changed from 0.09 mm (Example2) to 0.155 mm (Example 4).

Example 5

In Example 5, the image recording was conducted in the same manner asthe Example 2, except that a slanted amount of the C-directional markingline to the A-directional marking line was changed from 0.09 mm (Example2) to 0.02 mm (Example 5).

Example 6

In Example 6, the image recording was conducted in the same manner asthe Example 2, except that a slanted amount of the C-directional markingline to the A-directional marking line was changed from 0.09 mm (Example2) to 0.18 mm (Example 6).

Example 7

In Example 7, the image recording was conducted based on a laser beamscanning method illustrated in FIG. 21B (i.e., 4 A-directional markinglines, 3 C-directional marking lines, and no marking line was drawn in Bdirection), in the same manner as the Example 2, except that theirradiation power of the laser beam applied for marking the firstmarking line was increased by 10% of that of the laser beam applied formarking the first marking line in Example 2. In Example 7, theirradiation power of the laser beam for marking the first making linewas 21.0 W and that for marking the second marking line was 19.1 W.

Example 8

In Example 8, the image recording was conducted in the same manner asthe Example 2, except that the thermoreversible recording mediummanufactured in Manufacturing Example 1 (used in Example 2) was changedto the thermoreversible recording medium manufactured in ManufacturingExample 2

Comparative Example 1

In Comparative Example 1, the image recording was conducted in the samemanner as the Example 1 based on a laser beam scanning methodillustrated in FIG. 22A (i.e., 7 A-directional marking lines, 6B-directional marking lines, and no C-directional marking line) insteadof the laser beam scanning method illustrated in FIG. 21A, where a pitchwidth was set at 0.20 mm between adjacent A-directional marking lines,and a length of the A-directional marking line was set at 20 mm.

Comparative Example 2

In Comparative Example 2, the image recording was conducted in the samemanner as the Example 1 based on a laser beam scanning methodillustrated in FIG. 22B (i.e., 7 A-directional marking lines, noB-directional marking line, and no C-directional marking line) insteadof the laser beam scanning method illustrated in FIG. 21A, where a pitchwidth was set at 0.20 mm between adjacent A-directional marking lines,and a length of the A-directional marking line was set at 20 mm.

Comparative Example 3

In Comparative Example 3, the image recording was conducted in the samemanner as the Example 1 based on a laser beam scanning methodillustrated in FIG. 22C (i.e., 7 A-directional marking lines, noB-directional marking line, and no C-directional marking line) insteadof the laser beam scanning method illustrated in FIG. 21A, where a pitchwidth was set at 0.20 mm between adjacent A-directional marking lines,and a length of the A-directional marking line was set at 20 mm.

Image Erasure Example 9

In Example 9, a working distance was adjusted at 181 mm (a beamdiameter: 3.0 mm) and a scanning speed was adjusted at 1,000 mm/s in anLD marker device, and the solidly filled image recorded in a solidlyfilled marking area of the thermoreversible recording medium obtained inManufacturing Example 1 was erased based on the laser beam scanningmethod illustrated in FIG. 21A (i.e., 14 A-directional marking lines, 27B-directional marking lines, and 14 C-directional marking lines in thiscase). In Example 9, the image erasure was conducted such that a pitchwidth was set at 0.60 mm between an A-directional marking line and aC-directional marking line adjacent to the A-directional marking line, aslanted amount of the C-directional marking line to the A-directionalmarking line was set at 0.24 mm, and a length of the A-directionalmarking line was set at 40 mm.

Example 10

In Example 10, the image erasure was conducted based on a laser beamscanning method illustrated in FIG. 21B (i.e., 14 A-directional markinglines, 14 C-directional marking lines, and no B-directional markingline) instead of the laser beam scanning method illustrated in FIG. 21A.In Example 10, the solidly filled image was erased in the same manner asthe Example 9 where a pitch width was set at 0.60 mm between anA-directional marking line and a C-directional marking line adjacent tothe A-directional marking line, a slanted amount of the C-directionalmarking line to the A-directional marking line was set at 0.24 mm, and alength of the A-directional marking line was set at 40 mm.

Example 11

In Example 11, the image erasure was conducted in the same manner as theExample 10, except that a slanted amount of the C-directional line tothe A-directional line was changed from 0.24 mm (Example 10) to 0.13 mm(Example 11).

Example 12

In Example 12, the image erasure was conducted in the same manner as theExample 10, except that a slanted amount of the C-directional line tothe A-directional line was changed from 0.24 mm (Example 10) to 0.46 mm(Example 12).

Example 13

In Example 13, the image erasure was conducted in the same manner as theExample 10, except that a slanted amount of the C-directional line tothe A-directional line was changed from 0.24 mm (Example 10) to 0.08 mm(Example 13).

Example 14

In Example 14, the image erasure was conducted in the same manner as theExample 10, except that a slanted amount of the C-directional line tothe A-directional line was changed from 0.24 mm (Example 10) to 0.54 mm(Example 14).

Comparative Example 4

In Comparative Example 4, the image erasure was conducted based on thelaser beam scanning method illustrated in FIG. 22A (i.e., 28A-directional marking lines, 27 B-directional marking lines, and no Cdirectional marking line) instead of the laser beam scanning methodillustrated in FIG. 21A. The solidly filled image was erased in the samemanner as the Example 9, where a pitch width was set at 0.60 mm betweenadjacent A-directional marking lines, and a length of the A directionalline was set at 40 mm.

Comparative Example 5

In Comparative Example 5, the image erasure was conducted based on thelaser beam scanning method illustrated in FIG. 22B (i.e., 28A-directional marking lines, no B-directional marking line, and no Cdirectional marking line) instead of the laser beam scanning methodillustrated in FIG. 21A. The solidly filled image was erased in the samemanner as the Example 9, except that a pitch width was set at 0.60 mmbetween adjacent A-directional marking lines, and a length of the Adirectional line was set at 40 mm.

Comparative Example 6

In Comparative Example 6, the image erasure was conducted based on thelaser beam scanning method illustrated in FIG. 22C (i.e., 28A-directional marking lines, no B-directional marking line, and no Cdirectional marking line) instead of the laser beam scanning methodillustrated in FIG. 21A. The solidly filled image was erased in the samemanner as the Example 9, except that a pitch width was set at 0.60 mmbetween adjacent A-directional marking lines, and a length of the Adirectional line was set at 40 mm.

—Evaluation of Image Printing and Repeated Durability—

Table 1 illustrates printing time and irradiation power of the laserbeam in printing the solidly filled image when image density issaturated in Examples 1 through 8, and in Comparative Examples 1 through3.

Further, after the images were recorded in Examples 1 through 8 and inComparative Examples 1 through 3, the recorded images were erased basedon the image erasure method of Comparative Example 6 by applying a laserbeam with an erasure mean power, and the image processing including theimage recording and the image erasure was thus repeatedly carried out.Table 1 also includes an evaluation result of repeated durability havingthe number of times the solidly filled image density in the imagerecording process was 1.3 or less, or the number of times the unerasedimage density in the image erasing process exceeded 0.02.

Note that the solidly filled image density and the unerased imagedensity were measured based on a grayscale (Kodak Co., Ltd.) read by ascanner (Canoscan 4400 manufactured by Canon Inc.), and a correlationbetween the respective grayscale values and the respective imagedensities measured by a reflection densitometer (RD-914 manufactured byMachbeth Corp.) were computed. Accordingly, the respective grayscalevalues of the solidly filled images and the unerased images wereconverted into the respective image densities of the solidly filledimages and the unerased images.

TABLE 1 IMAGE PRINTING RE- SLANTED PEATED PRINT LASER AMOUNT/ DURA- MARKTIME POWER PITCH BILITY METHOD (ms) (W) WIDTH (times) Example 1 FIG. 21A30 20.0 0.450 500 Example 2 FIG. 21B 30 20.9 0.450 2450 Example 3 FIG.21B 30 20.0 0.225 590 Example 4 FIG. 21B 30 21.3 0.775 620 Example 5FIG. 21B 30 23.0 0.100 160 Example 6 FIG. 21B 30 23.5 0.900 200 Example7 FIG. 21B 30 19.1 0.450 3250 Example 8 FIG. 21B 30 21.8 0.450 20Comparative FIG. 22A 30 23.4 — 10 Example 1 Comparative FIG. 22B 30 23.9— 120 Example 2 Comparative FIG. 22C 41 25.2 — 1350 Example 3

—Image Erasing Properties—

The solidly filled image formed in the solidly filled image printingarea recorded in Example 2 was erased by sequentially changing from lowirradiation power (W) to high irradiation power of the applied laserbeam under image erasure conditions in Examples 9 to 14 and inComparative Examples 4 through 6, and image erasure time, an erasuremean power, and an erasure width were obtained. The results areillustrated in Table 2.

Note that the erasure mean power indicates irradiation power of thelaser beam applied to the thermoreversible recording medium where a basedensity of the thermoreversible recording medium was +0.02 or less basedon the base density of the thermoreversible recording medium obtainedbefore the solidly filled image was formed. The erasure mean power wasobtained by computing a mean between the maximum value and minimum valueof the irradiation power of the laser beam. Moreover, the erasure widthwas computed by (maximum value−minimum value)/(maximum value+minimumvalue).

Note that the base density of the thermoreversible recording medium wasmeasured in the same manner as those of the solidly filled image densityand the unerased image density.

TABLE 2 IMAGE ERASURE ERASE SLANTED ERASE MEAN AMOUNT/ ERASE TIME POWERERASED PITCH METHOD (s) (W) WIDTH WIDTH Example 9 FIG. 21A 1.21 26.00.18 0.400 Example 10 FIG. 21B 1.21 26.5 0.22 0.400 Example 11 FIG. 21B1.21 26.9 0.16 0.217 Example 12 FIG. 21B 1.21 26.7 0.17 0.767 Example 13FIG. 21B 1.21 27.3 0.07 0.133 Example 14 FIG. 21B 1.21 27.1 0.08 0.900Comparative FIG. 22A 1.21 27.0 0.00 — Example 4 Comparative FIG. 22B1.21 27.4 0.04 — Example 5 Comparative FIG. 22C 1.63 29.2 0.21 — Example6The marking control device, the laser application device, the markingcontrol method, the marking control program, and a computer-readablerecording medium embodying the marking control program according topreferred embodiments are described. However, they are not limited tothose specifically disclosed embodiments and various modifications andalteration may be made within the scope of the inventions described inthe claims.

The marking control method according to the embodiments is capable ofproviding excellent printing quality in recording or erasing an image,excellent repeated durability in forming the image, image-processing ina short time, and excellent applicability to a solidly filled image,barcode/QR code printing, and boldface character printing. Accordingly,the marking control method according to the embodiments may be suitablyused as a marking control method for marking recording media utilized ina physical distribution system and delivery system.

The disclosed embodiments may provide the marking control device, thelaser application device, the marking control method, the markingcontrol program, and the computer-readable recording medium embodyingsuch a marking control program capable of reducing a marking time inmarking an image while maintaining high quality of the marked image.

Embodiments of the present invention have been described heretofore forthe purpose of illustration. The present invention is not limited tothese embodiments, but various variations and modifications may be madewithout departing from the scope of the present invention. The presentinvention should not be interpreted as being limited to the embodimentsthat are described in the specification and illustrated in the drawings.

The present application is based on Japanese Priority Applications No.2009-240527 filed on Oct. 19, 2009, No. 2009-247295 filed on Oct. 28,2009, and No. 2010-201388 filed on Sep. 8, 2010, with the JapanesePatent Office, the entire contents of which are hereby incorporated byreference.

1. A marking control device for controlling a marking device that marksa target image on a thermoreversible recording medium by applying alaser beam thereto, the marking control device comprising: a markingposition determination unit configured to divide the target image into afirst marking line and a second marking line that are adjacent to eachother, and determine a marking position of each of the adjacent firstand second marking lines; a marking order determination unit configuredto determine a marking order of the adjacent first and second markinglines for marking the target image such that the second marking line ismarked in a direction opposite to a direction in which the first markingline is marked; an adjusting unit configured to adjust, when the firstmarking line is initially scanned and the second marking line isreciprocally scanned subsequent to the first marking line, a firstdistance between a first ending point of the first marking line and asecond starting point of the second marking line to be longer than asecond distance between a first starting point of the first marking lineand a second ending point of the second marking line, or a laser outputpower of the laser beam applied to a second starting point side of thesecond marking line to be lower than a laser output power of the laserbeam applied to a second ending point side of the second marking line;and a marking instruction generator unit configured to generate a set ofmarking instructions including the respective marking positions of thefirst and second marking lines and the marking order of the first andsecond marking lines.
 2. The marking control device as claimed in claim1, wherein the adjusting unit divides an interval between the firststarting point and the first ending point of the first marking line intoplural unit line components and an interval between the second startingpoint and the second ending point of the second marking line into pluralunit line components, and adjusts the laser output power of the laserbeam applied to the second starting point side of a unit line componentof the second marking line to be lower than the laser output power ofthe laser beam applied to the second ending point side of another unitline component of the second marking line subsequent to the unit linecomponent thereof.
 3. The marking control device as claimed in claim 1,wherein the adjusting unit adjusts the laser output power of the laserbeam applied to the second starting point side of the second markingline to be lower than the laser output power of the laser beam appliedto the second ending point side thereof by gradually lowering a markingspeed to mark the second marking line from the second starting point ofthe second marking line to the second ending point thereof.
 4. Themarking control device as claimed in claim 1, wherein the adjusting unitadjusts the laser output power of the laser beam applied to the secondstarting point side of the second marking line to be lower than thelaser output power of the laser beam applied to the second ending pointside thereof by gradually increasing the laser output power of the laserbeam applied to the second marking line from the second starting pointof the second marking line to the second ending point thereof.
 5. Themarking control device as claimed in claim 1, wherein the adjusting unitadjusts the first distance between the first ending point of the firstmarking line and the second starting point of the second marking line tobe longer than the second distance between the first starting point ofthe first marking line and the second ending point of the second markingline by marking the first marking line from the first starting point tothe first ending point and by marking the second marking line adjacentto the first marking line from the second starting point to the secondending point such that the second ending point of the second markingline is located in a line slanted toward the first starting point of thefirst marking line based on a line in parallel with the first markingline.
 6. The marking control device as claimed in claim 5, wherein theadjusting unit adjusts a third marking line to be marked from a thirdstarting point to a third ending point such that the third ending pointof the third marking line is located in a line slanted toward the secondstarting point of the second marking line based on a line in parallelwith the second marking line.
 7. The marking control device as claimedin claim 5, wherein the adjusting unit adjusts a laser beam not to beapplied to an interval between the first ending point of the firstmarking line and the second starting point of the second marking linelocated adjacent to the first marking line.
 8. The marking controldevice as claimed in claim 5, wherein the adjusting unit adjusts a laserbeam applied to the second starting point of the second marking line tobe located in a line perpendicular to the first marking line marked fromthe first end point of the first marking line.
 9. The marking controldevice as claimed in claim 6, wherein the adjusting unit adjusts thethird marking line to be marked in parallel with the first marking line.10. The marking control device as claimed in claim 5, wherein theadjusting unit adjusts irradiation energy of a laser beam that marks thefirst marking line to be higher than irradiation energy of a laser beamthat marks the second marking line.
 11. The marking control device asclaimed in claim 5, further comprising: a laser light source used inimage processing, wherein the laser light source is at least one of aYAG laser light, a fiber laser light, and a semiconductor laser light.12. The marking control device as claimed in claim 5, wherein awavelength of the laser beam for marking any of the marking lines is ina range of 700 to 1,500 nm.
 13. The marking control device as claimed inclaim 5, wherein the thermoreversible recording medium on which thetarget image is formed includes: a supporting member; a firstthermoreversible recording layer; a photothermal conversion layerconfigured to absorb light having a specific wavelength and convert theabsorbed light into heat; and a second thermoreversible recording layer,the first thermoreversible recording layer and the photothermalconversion layer and the second thermoreversible recording layer beingarranged in this order on the supporting member, and wherein the firstand second thermoreversible recording layers reversibly changerespective colors thereof based on respective temperatures of the firstand second thermoreversible recording layers.
 14. The marking controldevice as claimed in claim 13, wherein the first thermoreversiblerecording layer and the second thermoreversible recording layer includeleuco dyes and reversible developers.
 15. The marking control device asclaimed in claim 13, wherein a photothermal conversion material used forforming the photothermal conversion layer includes an absorption peak ina near-infrared region.
 16. The marking control device as claimed inclaim 15, wherein the photothermal conversion material used for formingthe photothermal conversion layer includes a phthalocyanine compound.17. A laser application device comprising: a laser oscillator configuredto generate a laser beam; a direction control mirror configured tocontrol a direction of the generated laser beam; a direction controlmotor configured to drive the direction control mirror; and the markingcontrol device as claimed in claim 1 configured to control an outputpower of the laser oscillator, and the driving of the direction controlmotor based on the set of the marking instructions.
 18. A markingcontrol method for controlling a marking device that marks a targetimage on a thermoreversible recording medium by applying a laser beamthereto, the marking control method comprising: dividing the targetimage into a first marking line and a second marking line that areadjacent to each other, and determining a marking position of each ofthe adjacent first and second marking lines; determining a marking orderof the adjacent first and second marking lines for marking the targetimage such that the second marking line is marked in a directionopposite to a direction in which the first marking line is marked;adjusting, when the first marking line is initially scanned and thesecond marking line is reciprocally scanned subsequent to the firstmarking line, a first distance between a first ending point of the firstmarking line and a second starting point of the second marking line tobe longer than a second distance between a first starting point of thefirst marking line and a second ending point of the second marking line,or a laser output power of the laser beam applied to a second startingpoint side of the second marking line to be lower than a laser outputpower of the laser beam applied to a second ending point side of thesecond marking line; and generating a set of marking instructionsincluding the respective marking positions of the first and secondmarking lines and the marking order of the first and second markinglines.
 19. (canceled)